Comparative morphology of the tapetum lucidum (among selected species)

Review: The influence of light on pig welfare

While several countries impose minimum light requirements for pig housing, it remains unknown whether these requirements are beneficial for pig welfare. Therefore, we aim to review the current knowledge on the effects of light on pig welfare. In this paper, we explain concepts defining light, discuss the relevance of vision for pigs and systematically review the effects of light on pig welfare. Systematic literature searches were performed in two databases to find studies about light and welfare-related topics, including behaviour, health, hormonal secretions and productivity. After screening, 63 studies were reviewed. According to literature, light is relevant in pigs' lives as they are diurnal animals and use vision in combination with other senses to, for example, locate food and interact with conspecifics. Throughout this paper, the investigated light parameters are photoperiod, intensity and spectrum. Pigs seem to have p for a certain light intensity and spectrum, but these preferences vary over production phases. Photoperiod influences feed intake and growth, especially in piglets, but no conclusion can be drawn because of contradictory results. Furthermore, pigs' activity patterns adapt to the provided light schedule and show a diurnal rhythm with higher activity during lit hours. Photoperiod also plays a role in the diurnal secretion of hormones. Cortisol secretion increases shortly before the moment of light onset, and melatonin secretion is influenced by the light and dark contrast with a nocturnal rise after light offset. Some behaviours are impacted by light intensity; for instance, dim conditions are associated with resting and bright conditions with elimination behaviour. Moreover, a few studies showed that in dimmer conditions, more negative social interactions occur, while brighter conditions lead to more positive interactions. Lastly, even though light spectrum is the least explored light parameter, several studies showed that UV B light can activate the cutaneous synthesis of vitamin D3. A limitation in the current literature is that several studies tested light treatments differing in more than one light parameter, making the interpretation of each light parameter difficult. Moreover, most studies do not provide information on other light parameters not targeted by the study, particularly on light spectrum. Some clear knowledge gaps that emerged from this review are on light spectrum and on affective states of pigs in relation to light.

Feline eye-inspired artificial vision for enhanced camouflage breaking under diverse light conditions

Biologically inspired artificial vision research has led to innovative robotic vision systems with low optical aberration, wide field of view, and compact form factor. However, challenges persist in object detection and recognition against complex backgrounds and varied lighting. Inspired by the feline eye, which features a vertically elongated pupil and tapetum lucidum, this study introduces an artificial vision system designed for superior object detection and recognition in a monocular framework. Using a slit-like elliptical aperture and a patterned metal reflector beneath a hemispherical silicon photodiode array, the system reduces excessive light and enhances photosensitivity. This design achieves clear focus under bright light and enhanced sensitivity in dim conditions. Theoretical and experimental analyses demonstrate the system's ability to filter redundant information and detect camouflaged objects in diverse lighting, representing a substantial advancement in monocular camera technology and the potential of biomimicry in optical innovations.

Understanding the Solid-State Structure of Riboflavin through a Multitechnique Approach

Crystalline riboflavin (vitamin B2) performs an important biological role as an optically functional material in the tapetum lucidum of certain animals, notably lemurs and cats. The tapetum lucidum is a reflecting layer behind the retina, which serves to enhance photon capture and vision in low-light settings. Motivated by the aim of rationalizing its biological role, and given that the structure of biogenic solid-state riboflavin remains unknown, we have used a range of experimental and computational techniques to determine the solid-state structure of synthetic riboflavin. Our multitechnique approach included microcrystal XRD, powder XRD, three-dimensional electron diffraction (3D-ED), high-resolution solid-state 13C NMR spectroscopy, and dispersion-augmented density functional theory (DFT-D) calculations. Although an independent report of the crystal structure of riboflavin was published recently, our structural investigations reported herein provide a different interpretation of the intermolecular hydrogen-bonding arrangement in this material, supported by all the experimental and computational approaches utilized in our study. We also discuss, more generally, potential pitfalls that may arise in applying DFT-D geometry optimization as a bridging step between structure solution and Rietveld refinement in the structure determination of hydrogen-bonded materials from powder XRD data. Finally, we report experimental and computational values for the refractive index of riboflavin, with implications for its optical function.

Morphological Characteristics of Retinal Ganglion Cells in the Retinas of Giant Pandas (Ailuropoda melanoleuca)

Vision plays a crucial role in the survival of animals, and the visual system has particularly selectively evolved in response to the visual environment, ecological niche, and species habitats in vertebrate species. To date, a horizontal streak of retinal ganglion cell (RGC) distribution pattern is observed across mammal species. Here, we report that the giant panda's vertically oriented visual streak, combined with current evidence of the animal's forward-placed eyes, ocular structure, and retinal neural topographic distribution patterns, presents the emergence of a well-adapted binocular visual system. Our results suggest that the giant panda may use a unique way to processing binocular visual information. Results of mathematical simulation are in favor of this hypothesis. The topographic distribution properties of RGCs reported here could be essential for understanding the visual adaptation and evolution of this living fossil.

Systematic analysis of ocular features and responses of cultured spotted wolffish (Anarhichas minor)

A better understanding of unique anatomical and functional features of the visual systems of teleost fish could provide key knowledge on how these systems influence the health and survival of these animals in both wild and culture environments. We took a systematic approach to assess some of the visual systems of spotted wolffish (Anarhichas minor), a species of increasing importance in North Atlantic aquaculture initiatives. The lumpfish (Cyclopterus lumpus) was included in these studies in a comparative manner to provide reference. Histology, light and electron microscopy were used to study the spatial distribution and occurrence of cone photoreceptor cells and the nature of the retinal tissues, while immunohistochemistry was used to explore the expression patterns of two photoreceptor markers, XAP-1 and XAP-2, in both species. A marine bacterial infection paradigm in lumpfish was used to assess how host-pathogen responses might impact the expression of these photoreceptor markers in these animals. We define a basic photoreceptor mosaic and present an ultrastructural to macroscopic geographical configuration of the retinal pigment tissues in both animals. Photoreceptor markers XAP-1 and XAP-2 have novel distribution patterns in spotted wolffish and lumpfish retinas, and exogenous pathogenic influences can affect the normal expression pattern of XAP-1 in lumpfish. Live tank-side ophthalmoscopy and spectral domain optical coherence tomography (SD-OCT) revealed that normal cultured spotted wolffish display novel variations in the shape of the retinal tissue. These two complementary imaging findings suggest that spotted wolffish harbour unique ocular features not yet described in marine teleosts and that visual function might involve specific retinal tissue shape dynamics in these animals. Finally, extensive endogenous biofluorescence is present in the retinal tissues of both animals, which raises questions about how these animals might use retinal tissue in novel ways for visual perception and/or communication. This work advances fundamental knowledge on the visual systems of two economically important but now threatened North Atlantic teleosts and provides a basic foundation for further research on the visual systems of these animals in health versus disease settings. This work could also be useful for understanding and optimizing the health and welfare of lumpfish and spotted wolffish in aquaculture towards a one health or integrative perspective.

Morphological examination of the visual system and orbital region in the red panda (Ailurus fulgens fulgens)

OBJECTIVES

The red panda is currently the only surviving member of the Ailuridae family in the Caniformia suborder. In this study, we provide data on anatomical, morphometric, histological and histochemical examination of the orbital region, eyelids, orbital gland, and eye tunics in two adult males Ailurus fulgens fulgens from the Wroclaw Zoological Garden, Poland.

METHODS

The study involved morphometric analysis of the eyeball and selected accessory organs of the eye, along with analysis of the bony orbit, including its morphometry, macroscopic, and microscopic evaluation. Microscopic evaluation encompassed histological and histochemical staining, with the former involving hematoxylin & eosin (H&E), Movat pentachrome, picro-Mallory trichrome, Fontana-Masson, and the latter including PAS, AB pH 1.0, AB pH 2.5; AB pH 2.5/PAS, and HDI.

RESULTS

The upper (UE) and lower (LE) eyelids presented well-developed tarsal glands, sebaceous glands, and a characteristic simple alveolar gland (producing a mucous secretion). The palpebral part of the lacrimal gland was present. A single lymphoid follicle was observed only in the upper eyelids. The superficial gland of the third eyelid (SGTE) was a multilobar acinar complex that produces mucous secretion and is contained within the interlobular ducts of numerous aggregates of lymph nodes. The third eyelid (TE) was T-shaped and composed of hyaline tissue, containing CALT. The lacrimal gland (LG) also revealed a multilobar acinar complex that produced mucous secretion, with a single lymphoid follicle. The cornea consisted of 4 layers, as Bowman's membrane was absent. The Vogt palisades composed of 7-10 layers of epithelial cells were demonstrated. The pupil was horizontally ovoid at rest (post-mortem). The sphincter pupil and the dilator pupil were well developed. Macroscopically, the tapetum lucidum appeared as a milky, non-opalescent crescent. Histologically, the choroidal tapetum lucidum cellulosum consisted of 5 to 9 layers of loosely packed oval cells. The retina showed a composition similar to that of terrestrial nocturnal carnivores.

CONCLUSIONS

The results of our research indicate that the anatomical features of the eye and orbital region in the red panda share similarities with those described in the Musteloidea clade, as well as the Canidae and Ursidae families.

Bio-Inspired Crystalline Core-Shell Guanine Spherulites

Spherical particles with diameters within the wavelength of visible light, known as spherulites, manipulate light uniquely due to their spatial organization and their structural birefringence. Most of the known crystalline spherulites are branched, and composed of metals, alloys, and semi-crystalline polymers. Recently, a different spherulite architecture is discovered in the vision systems of decapod crustaceans - core-shell spherulites composed of highly birefringent (Δ n ≈ 30 % $\Delta n \approx \ 30\%$ ) organic single-crystal platelets, with exceptional optical properties. These metastructures, which efficiently scatter light even in dense aqueous environments, have no synthetic equivalence and serve as a natural proof-of-concept as well as synthetic inspiration for thin scattering media. Here, the synthesis of core-shell spherulites composed of guanine crystal platelets ((Δ n ≈ 25 % $\Delta n \approx 25\%$ ) is presented in a two-step emulsification process in which a water/oil/water emulsion and induced pH changes are used to promote interfacial crystallization. Carboxylic acids neutralize the dissolved guanine salts to form spherulites composed of single, radially stacked, β-guanine platelets, which are oriented tangentially to the spherulite surface. Using Mie theory calculations and forward scattering measurements from single spherulites, it is found that due to the single-crystal properties and orientation, the synthetic spherulites possess a high tangential refractive index, similarly to biogenic particles.

Wearable Alcohol Monitoring Device for the Data-Driven Transcutaneous Alcohol Diffusion Model

Wearable alcohol monitoring devices demand noninvasive, real-time measurement of blood alcohol content (BAC) reliably and continuously. A few commercial devices are available to determine BAC noninvasively by detecting transcutaneous diffused alcohol. However, they suffer from a lack of accuracy and reliability in the determination of BAC in real time due to the complex scenario of the human skin for transcutaneous alcohol diffusion and numerous factors (e.g., skin thickness, kinetics of alcohol, body weight, age, sex, metabolism rate, etc.). In this work, a transcutaneous alcohol diffusion model has been developed from real-time captured data from human wrists to better understand the kinetics of diffused alcohol from blood to different skin epidermis layers. Such a model will be a footprint to determine a base computational model in larger studies. Eight anonymous volunteers participated in this pilot study. A laboratory-built wearable blood alcohol content (BAC) monitoring device collected all the data to develop this diffusion model. The proton exchange membrane fuel cell (PEMFC) sensor was fabricated and integrated with an nRF51822 microcontroller, LMP91000 miniaturized potentiostat, 2.4 GHz transceiver supporting Bluetooth low energy (BLE), and all the necessary electronic components to build this wearable BAC monitoring device. The %BAC data in real time were collected using this device from these volunteers' wrists and stored in the end device (e.g., smartphone). From the captured data, we demonstrate how the volatile alcohol concentration on the skin varies over time by comparing the alcohol concentration in the initial stage (= 10 min) and later time (= 100 min). We also compare the experimental results with the outputs of three different input profiles: piecewise linear, exponential linear, and Hoerl, to optimize the developed diffusion model. Our results demonstrate that the exponential linear function best fits the experimental data compared to the piecewise linear and Hoerl functions. Moreover, we have studied the impact of skin epidermis thickness within ±20% and demonstrate that a 20% decrease in this thickness results in faster dynamics compared to thicker skin. The model clearly shows how the diffusion front changes within a skin epidermis layer with time. We further verified that 60 min was roughly the time to reach the maximum concentration, Cmax, in the stratum corneum from the transient analysis. Lastly, we found that a more significant time difference between BACmax and Cmax was due to greater alcohol consumption for a fixed absorption time.

Biomimetic synthesis of single-crystalline anhydrous xanthine nanoplates in an aqueous solution with high reflectivity

Biogenic purine crystals can function in vision as light scatters, mirrors, and multilayer reflectors and produce structural colors or depolarization for camouflage. Xanthine crystals form irregular multifocal mirrors in the median ocellus of Archaeognatha. It is important to broaden the study of crystallization strategies to obtain organic crystals with purine rings in the laboratory. In this work, a facile one-step synthesis route to fabricate bio-inspired xanthine crystals is reported for the first time. The obtained rhomboidal xanthine nanoplates have similar morphology and size to biogenic xanthine crystals. Their length and thickness are about 2-4 μm and 50 nm, respectively. Lattice parameters, crystal structure, formation mechanism and optical properties of synthetic single-crystalline xanthine nanoplates were investigated in detail in this work. The obtained xanthine nanoplate crystals are proposed to be anhydrous xanthine with monoclinic symmetry, and the xanthine nanoplates mainly expose the (100) plane. It is proposed that the anhydrous xanthine nanoplates are formed via an amorphous xanthine intermediate precursor. The synthetic anhydrous xanthine nanoplates exhibit excellent optical properties, including high diffuse reflectivity, strong depolarization and pearlescent luster. This work provides a new design to synthesize bio-inspired organic molecular crystals with excellent optical properties.

Carotenoid cleavage enzymes evolved convergently to generate the visual chromophore

The retinal light response in animals originates from the photoisomerization of an opsin-coupled 11-cis-retinaldehyde chromophore. This visual chromophore is enzymatically produced through the action of carotenoid cleavage dioxygenases. Vertebrates require two carotenoid cleavage dioxygenases, β-carotene oxygenase 1 and retinal pigment epithelium 65 (RPE65), to form 11-cis-retinaldehyde from carotenoid substrates, whereas invertebrates such as insects use a single enzyme known as Neither Inactivation Nor Afterpotential B (NinaB). RPE65 and NinaB couple trans-cis isomerization with hydrolysis and oxygenation, respectively, but the mechanistic relationship of their isomerase activities remains unknown. Here we report the structure of NinaB, revealing details of its active site architecture and mode of membrane binding. Structure-guided mutagenesis studies identify a residue cluster deep within the NinaB substrate-binding cleft that controls its isomerization activity. Our data demonstrate that isomerization activity is mediated by distinct active site regions in NinaB and RPE65-an evolutionary convergence that deepens our understanding of visual system diversity.

Using a smartphone-based digital fundus camera for screening of retinal and optic nerve diseases in veterinary medicine: A preliminary investigation

BACKGROUND

Ophthalmoscopy is a valuable tool in clinical practice. We report the use of a novel smartphone-based handheld device for visualisation and photo-documentation of the ocular fundus in veterinary medicine.

METHODS

Selected veterinary patients of a referral ophthalmology service were included if one or both eyes had clear ocular media, allowing for examination of the fundus. Following pharmacological mydriasis, fundic images were obtained with a handheld fundus camera (Volk VistaView). For comparison, the fundus of a subset of animals was also imaged with a veterinary-specific fundus camera (Optomed Smartscope VET2).

RESULTS

The large field of view achieved by the Volk VistaView allowed for rapid and thorough observation of the ocular fundus in animals, providing a tool to visualise and record common pathologies of the posterior segment. Captured fundic images were sometimes overexposed, with the tapetal fundus artificially appearing hyperreflective when using the Volk VistaView camera, a finding that was less frequent when activating a 'veterinary mode' that reduced the sensitivity of the camera's sensor. The Volk VistaView compared well with the Optomed Smartscope VET2.

LIMITATION

The main study limitation was the small sample size.

CONCLUSIONS

The Volk VistaView camera was easy to use and provided good-quality fundic images in veterinary patients with healthy or diseased eyes, offering a wide field of view that was ideal for screening purposes.

Retinal response to light exposure in BEST1-mutant dogs evaluated with ultra-high resolution OCT

Mutations in BEST1 cause an autosomal recessive disease in dogs where the earliest changes localize to the photoreceptor-RPE interface and show a retina-wide micro-detachment that is modulated by light exposure. The purpose of this study was to define the spatial and temporal details of the outer retina and its response to light with ultra-high resolution OCT across a range of ages and with different BEST1 mutations. Three retinal regions were selected in each eye: near the fovea-like area, near the optic nerve, both in the tapetal area, and inferior to the optic nerve in the non-tapetal area. The OS+ slab thickness was defined between the peak near the junction of inner and outer segments (IS/OS) and the transition between basal RPE, Bruch membrane, choriocapillaris and proximal tapetum (RPE/T). In wildtype (WT) dogs, two tapetal regions showed additional hyperscattering OCT peaks within the OS+ slab likely representing cone and rod outer segment tips (COST and ROST). The inferior non-tapetal region of WT dogs had only one of these peaks, likely ROST. In dogs with BEST1 mutations, all three locations showed a single peak, likely suggesting optical silence of COST. Light-dependent expansion of the micro-detachment by about 10 um was detectable in both tapetal and non-tapetal retina across all ages and BEST1 mutations.

The Synergistic Effect on the Mimetic Optical Structure of Feline Eyes toward Household Health Monitoring of Acute and Chronic Diseases

A breakthrough in the performance of bionic optical structures will only be achieved if we can obtain an in-depth understanding of the synergy mechanisms operating in natural optical structures and find ways to imitate them. In this work, inspired by feline eyes, an optical substrate that takes advantage of a synergistic effect that occurs between resonant and reflective structures was designed. The synergistic effect between the reflective and resonant components leads to a Raman enhancement factor (EF) of 1.16 × 107, which is much greater than that achieved using the reflective/resonant cavities on their own. Finite-difference time-domain (FDTD) simulations and experimental results together confirm that the mechanism of this synergistic effect is achieved by realizing multiple reflections and repeated absorptions of light, generating a strong local electric field. Thus, a 2-3 order of magnitude increase in sensitivity could be achieved. More importantly, with the homemade centrifugal device, above optical substrates were further used to develop a rapidly highly sensitive household health monitoring system (detection time <3 min). It can thus be used to give early warning of acute diseases with high risk (e.g., acute myocardial infarction (AMI) and cerebral peduncle). Due to the good reusability and storability (9% and 8% reduction in EF after washing 30 times and 9 months of storage, respectively) of the substrates, the substrates thus reduce detection costs (to ∼$1), making them much cheaper to use than the current gold-standard methods (e.g., ∼$16 for gout detection).

Surface-Guided Crystallization of Xanthine Derivatives for Optical Metamaterial Applications

Numerous bio-organisms employ template-assisted crystallization of molecular solids to yield crystal morphologies with unique optical properties that are difficult to reproduce synthetically. Here, a facile procedure is presented to deposit bio-inspired birefringent crystals of xanthine derivatives on a template of single-crystal quartz. Crystalline sheets that are several millimeters in length, several hundred micrometers in width, and 300-600 nm thick, are obtained. The crystal sheets are characterized with a well-defined orientation both in and out of the substrate plane, giving rise to high optical anisotropy in the plane parallel to the quartz surface, with a refractive index difference Δn ≈ 0.25 and a refractive index along the slow axis of n ≈ 1.7. It is further shown that patterning of the crystalline stripes with a tailored periodic grating leads to a thin organic polarization-dependent diffractive meta-surface, opening the door to the fabrication of various optical devices from a platform of small-molecule based organic dielectric crystals.

The organ of vision morphology of the southern two-toed sloth (Choloepus didactylus Linnaeus, 1758; Pilosa, Choloepodidae)

The Choloepus didactylus is a species belonging to the Choloepodidae family of the Folivora suborder. This study concerns the anatomical, morphometrical, histological and histochemical examination of the eye tunics, eyelids and orbital glands in the three adult Choloepus didactylus coming from the Wroclaw Zoological Garden. The cornea consists of four layers since Bowman's membrane was absent. The presence of palisades of Vogt formed from 14/15 to 20/21 layers of epithelial cells was demonstrated. Macroscopically, the tapetum lucidum was not identified, while degenerative choroidal tapetum lucidum cellulosum was found microscopically. The ciliary muscle was found with our histological approach. The pupil was round in shape (post-mortem). The presence of tarsal glands has not been demonstrated in both eyelids. The conjunctiva-associated lymphoid tissue (CALT) has been shown in the upper and lower eyelids. The superficial gland of the third eyelid produced a seromucous secretion. The third eyelid was shaped like a curved arch and composed of hyaline cartilage. The deep gland of the third eyelid was big and multilobar acinar simple with serous character. The lacrimal gland produced mucous secretion. The results of our research indicate that the features of the eye anatomy in the southern two-toed sloth (C. didactylus) are also typical of the Folivora suborder and have common features and differences with Vermilingua.

CLINICAL AND HISTOPATHOLOGIC OCULAR FINDINGS IN AQUARIUM-HOUSED COWNOSE RAYS (RHINOPTERA BONASUS)

Cownose rays (Rhinoptera bonasus) are susceptible to ocular disease with their prominent globes, but despite being popular animals housed in aquaria, there is little published information about their normal ocular anatomy and common pathologic ocular findings. A total of 63 live cownose rays (CNR) from three unrelated, separately housed groups had ocular examinations, and 5 adult rays were selected for ocular ultrasound. All examinations were performed out of the water, and most without anesthesia. Clinical findings were described, categorized, and scored by severity. Sixty-two of 63 rays (123 eyes) had clinical abnormalities, including 110 eyes with corneal pathology (mild = 76, moderate/severe = 34) and 74 eyes with intraocular pathology (mild = 44, moderate/severe = 30). Grey-to-white corneal opacities were the most common pathology (n = 58 rays/100 eyes) followed by cataracts (n = 41 rays/58 eyes), then persistent (or dysplastic) pupillary membranes (n = 14 rays/15 eyes). Most pathologic findings appeared inactive, but one aquarium had several CNR with active ocular pathology. There was a significant association between the diagnosis of moderate/severe corneal and intraocular pathology with age (P = 0.008 and P = 0.014, respectively) and weight (P = 0.001 and P = 0.039, respectively), as well as moderate/severe corneal pathology and group sampled (P = 0.03). There were no other significant variables identified. Additionally, histopathology of 14 eyes (11 rays) from two different facilities were examined, with keratitis (n = 8) and uveitis (n = 2) as the most common lesions. This study shows a high prevalence of pathologic ocular findings in cownose ray eyes with heavier adults more likely to be affected than lighter juveniles. Comprehensive ocular evaluation is important in this species and serial ocular exams and future studies should be pursued to monitor ocular disease progression and better understand possible etiologies.

The importance of auditory, olfactory, and visual cues for insect foraging in owl monkeys (Aotus nancymaae)

Nocturnal mammals have unique sensory adaptations to facilitate foraging at night. Owl monkeys (Aotus spp.) are pair-living nocturnal platyrrhines adept at capturing insect prey under low-light conditions. Owl monkeys use acoustic and chemical cues in intraspecific communication and use olfaction to detect fruit as they forage. We conducted an experiment to determine which cues (auditory, olfactory, and visual) Aotus nancymaae rely upon when foraging for insects. We scored the behavior of 23 captive owl monkeys during a series of trials in which monkeys were provided sensory boxes with insect cues either present (experimental box) or absent (control box). Each cue was tested alone and in combination with all other cues (multimodal cues). We used generalized linear mixed models to determine which cues elicited the greatest behavioral response. Owl monkeys approached and spent more time near experimental boxes than control boxes. Male owl monkeys were quicker than their female partners to approach the sensory boxes, suggesting that males may be less neophobic than females. The owl monkeys exhibited behaviors associated with olfaction and foraging (e.g., sneezing, trilling) during trials with multimodal cues and when only olfactory cues were present. When only visual or auditory cues were present, owl monkeys exhibited fewer foraging-related behaviors. After approaching a sensory box, however, they often touched boxes containing visual cues. A. nancymaae may rely on olfactory cues at night to detect a food source from several meters away and then rely more on visual cues once they are closer to the food source. Their use of sensory cues during insect foraging differs from nocturnal strepsirrhines, possibly reflecting physiological constraints associated with phylogeny, given that owl monkeys evolved nocturnality secondarily from a more recent diurnal ancestor.

Ex Vivo analysis of ultraviolet radiation transmission through ocular media and retina in select species

The aim of this study was to assess the transmission of the ultraviolet (UV) radiation (200-400 nm) through intact enucleated globes of different species (dogs, cats, pigs, rabbits, horses, and humans) using spectrophotometry. Globes of cats (n = 6), dogs (n = 18), pigs (n = 10), rabbits (n = 6), horses (n = 10), and humans (n = 4) were analyzed. A 5-10 mm circular area of sclera and choroid from the posterior aspect of the globe was removed under a surgical microscope, leaving the retina intact in all species except the horse. Glass coverslips were added in horses and rabbits due to retinal and globe fragility. The %T of wavelengths from 200 to 800 nm were measured through the ocular media (cornea, aqueous humor, lens, and vitreous humor) and retina, and compared between species. The globes of cats and dogs allowed the most amount of UV radiation transmission, while those of pigs and humans allowed the least amount of UV radiation transmission. A small amount of UV radiation transmission through the ocular media was detected in the rabbit and horse. Results from this study will support further vision research that may be used to train companion, working, and service animals.

Enrichment of Brain n-3 Docosapentaenoic Acid (DPA) and Retinal n-3 Eicosapentaenoic Acid (EPA) in Lambs Fed Nannochloropsis oceanica Microalga

Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have special physiological functions in both brain and retinal tissues that are related to the modulation of inflammatory processes and direct effects on neuronal membrane fluidity, impacting mental and visual health. Among them, the long-chain (LC) n-3 PUFAs, as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are of special importance. Scarce data are available about the fatty acid (FA) composition of the ruminant brain in response to dietary intervention. However, we decided to examine the brain and retina FA composition of lambs supplemented with an EPA-rich microalga feed for 21 days, as it is known that despite the extensive biohydrogenation of dietary PUFAs in the rumen, ruminants can selectively accumulate some n-3 LC-PUFAs in their brain and retinal tissues. Twenty-eight male lambs were fed a control diet, or the same diet further supplemented with Nannochloropsis sp. microalga. Their brains and retina were collected for FA characterization. Overall, the brain FA profile remained unchanged, with little alteration in omega-3 docosapentaenoic acid (DPA) enhancement in both the hippocampus and prefrontal cortex. Retinal tissues were particularly responsive to the dietary intervention, with a 4.5-fold enhancement of EPA in the freeze-dried-fed lambs compared with the control lambs. We conclude that retinal tissues are sensitive to short-term n-3 PUFA supplementation in lambs.

The evolutionary history and spectral tuning of vertebrate visual opsins

Many animals depend on the sense of vision for survival. In eumetazoans, vision requires specialized, light-sensitive cells called photoreceptors. Light reaches the photoreceptors and triggers the excitation of light-detecting proteins called opsins. Here, we describe the story of visual opsin evolution from the ancestral bilaterian to the extant vertebrate lineages. We explain the mechanisms determining color vision of extant vertebrates, focusing on opsin gene losses, duplications, and the expression regulation of vertebrate opsins. We describe the sequence variation both within and between species that has tweaked the sensitivities of opsin proteins towards different wavelengths of light. We provide an extensive resource of wavelength sensitivities and mutations that have diverged light sensitivity in many vertebrate species and predict how these mutations were accumulated in each lineage based on parsimony. We suggest possible natural and sexual selection mechanisms underlying these spectral differences. Understanding how molecular changes allow for functional adaptation of animals to different environments is a major goal in the field, and therefore identifying mutations affecting vision and their relationship to photic selection pressures is imperative. The goal of this review is to provide a comprehensive overview of our current understanding of opsin evolution in vertebrates.

Functional contextual implementation of an evolutionary, entropy-based, and embodied free energy framework: Utilizing Lagrangian mechanics and evolutionary game theory's truth vs. fitness test of the veridicality of phenomenological experience

The Bayesian approach of cognitive science largely takes the position that evolution drives perception to produce precepts that are veridical. However, some efforts utilizing evolutionary game theory simulations have shown that perception is more likely based on a fitness function, which promotes survival rather than promoting perceptual truth about the environment. Although these findings do not correspond well with the standard Bayesian approach to cognition, they may correspond with a behavioral functional contextual approach that is ontologically neutral (a-ontological). This approach, formalized through a post-Skinnerian account of behaviorism called relational frame theory (RFT), can, in fact, be shown to correspond well with an evolutionary fitness function, whereby contextual functions form that corresponds to a fitness function interface of the world. This fitness interface approach therefore may help provide a mathematical description for a functional contextual interface of phenomenological experience. Furthermore, this more broadly fits with a neurological active inference approach based on the free-energy principle (FEP) and more broadly with Lagrangian mechanics. These assumptions of how fitness beats truth (FBT) and FEP correspond to RFT are then discussed within a broader multidimensional and evolutionary framework called the extended evolutionary meta-model (EEMM) that has emerged out of the functional contextual behavioral science literature to incorporate principles of cognition, neurobiology, behaviorism, and evolution and are discussed in the context of a novel RFT framework called "Neurobiological and Natural Selection Relational Frame Theory" (N-frame). This framework mathematically connects RFT to FBT, FEP, and EEMM within a single framework that expands into dynamic graph networking. This is then discussed for its implications of empirical work at the non-ergodic process-based idiographic level as applied to individual and societal level dynamic modeling and clinical work. This discussion is framed within the context of individuals that are described as evolutionary adaptive and conscious (observer-self) agents that minimize entropy and can promote a prosocial society through group-level values and psychological flexibility.

Characterization of nonpathological intrascleral cartilage in the domestic sheep (Ovis aries)

ABSTRACT: Birds, cartilaginous and teleost fish, reptiles, and some amphibians have intrascleral cartilage and/or bone; however, these are rarely reported in therian mammals. This study aimed to investigate and characterize a nonpathological formation of cartilage in the posterior sclera of sheep macroscopically, histologically, and by immunohistochemical exam (IHC). Ninety eyes from 45 domestic sheep were collected, underwent gross examination, fixed in formalin, and embedded in paraffin for the microscopical assessment. Sections with histological shreds of cartilage were selected to perform IHC to confirm the presence of cartilage. Intrascleral cartilage was detected in 60 eyeballs (66.66%) from 37 sheep (82.22%). A slight whitish thickening was grossly seen in the posterior sclera. The histologic exam revealed a few scattered, isolated chondrocytes to larger aggregates of cartilaginous islands in the posterior sclera. Eighteen (30%) of 60 eyeballs revealed marked anti-collagen type II immunolabeling. The development of cartilaginous structures in the eyes is considered rare in mammalian animals. The high occurrence of intrascleral cartilage in the examined sheep eyes suggests that this finding corresponds to an anatomical component of sheep sclera, despite the age, breed, or body condition.

The glow of the night: The tapetum lucidum as a co-adaptation for the inverted retina

The vertebrate retina is said to be inverted because the photoreceptors are oriented in the posterior direction and are thus unable to maximize photodetection under conditions of low illumination. The tapetum lucidum is a photoreflective structure located posterior to the photoreceptors in the eyes of some fish and terrestrial animals. The tapetum reflects light forward, giving incident photons a "second chance" to collide with a photoreceptor, substantially enhancing retinal photosensitivity in dim light. Across vertebrates (and arthropods), there are a wide variety of tapeta that vary in structure, chemical composition, and even tissue architecture, indicating repeated convergent evolution. To date, the tapetum has not been observed in any cephalopod, however, which also possess a camera-like eye, but with the retinal photoreceptors oriented in the anterior direction. We therefore hypothesize that the tapetum lucidum is a compensatory adaptation for the suboptimal design of the inverted retina of vertebrates.

Anatomical features for an adequate choice of the experimental animal model in biomedicine: III. Ferret, goat, sheep, and horse

The anatomical characteristics of each of the many species today employed in biomedical research are very important when selecting the correct animal model(s), especially for conducting translational research. In previous papers, these features have been considered for fish (D'Angelo et al. Ann. Anat, 2016, 205:75), the most common laboratory rodents, rabbits, and pigs (Lossi et al. 2016). I here follow this line of discussion by dealing with the importance of proper knowledge of ferrets, goats, sheep, and horses' main anatomical features in translational research.

Reindeer eyes seasonally adapt to ozone-blue Arctic twilight by tuning a photonic tapetum lucidum

Reindeer are the only mammal known to seasonally adapt their eyes to the extremely blue colour of the extended twilight that occupies a large part of the winter 24 h cycle in their Arctic habitat. We describe the atmospheric phenomenon that results in this extreme spectral change in light environment. Reflectance spectroscopy is used to characterize the photonic nanostructure that generates the reflective region of the tapetum lucidum behind the retina. A model is proposed to explain the reversible reformatting of the reflector by seasonal changes in the volume of interstitial fluid within the two-dimensional photonic crystal of parallel collagen fibrils. This model is tested by allowing slow evaporation of the fluid from both summer and winter tapetum surfaces while monitoring changes in the reflectance spectrum. Coupled variations in the spacing and the degree of order of the fibril packing can transform the typical gold-turquoise colour of such a tapetal reflector to a deep blue that matches the peak spectral irradiance of twilight. The mechanism we describe might be applied by other animals with similar tapeta that experience prolonged changes in light environment.

Multilayer subwavelength gratings or sandwiches with periodic structure shape light reflection in the tapetum lucidum of taxonomically diverse vertebrate animals

Eye shine in the dark has attracted many researchers to the field of eye optics, but the initial studies of subwavelength arrangements in tapetum began only with the development of electronic microscopy at the end of the 20th century. As a result of a number of studies, it was shown that the reflective properties of the tapetum are due to their specialized cellular subwavelength microstructure (photonic crystals). These properties, together with the mutual orientation of the crystals, lead to a significant increase in reflection, which, in turn, enhances the sensitivity of the eye. In addition, research confirmed that optical mechanisms of reflection in the tapetum are very similar even for widely separated species. Due to progress in the field of nano-optics, researchers now have a better understanding of the main principles of this phenomenon. In this review, we summarize electron microscopic and functional studies of tapetal structures in the main vertebrate classes. This allows data on the microstructure of the tapetum to be used to improve our understanding of the visual system.

Morphological Aspects and Microscopic Analyses of Fibrous Tunic and Uveal Components in Bovine Eye

This study aimed to reveal the anatomical features of the bovine eye by scanning electron and light microscopic methods. For this purpose, a total of 40 eyes were evaluated. Gross and microscopic characteristics of the cornea, sclera, ciliary body, choroid, iris, and lens were determined. Bowman's and Descemet's membranes of the cornea were quite dense and prominent. Collagen lamellae of the cornea were wavy in the periphery and more parallel to the basal and metachromatic fibroblasts were noted. Three to four ciliary plicae merged to form ciliary processes. The presence of prominent intermediate bands connecting the ciliary plicae was determined. The zonular fibrils merged and attached to the lens in the form of thick zonular bands. A dense corpora nigra was present at the rectangular pupillary border of the iris. Tapetum fibrosum, consisting of polygonal tapetal cells, was in blue-yellow-green color and covered most of the choroid. A complex drainage system consisting of trabecular meshwork, angular aqueous plexus, ciliary sinus, and scleral venous vessels localized in a fairly wide iridocorneal angle was identified. Identifying structural features of the bovine eye is very important and useful for pathological evaluations, understanding species-specific physiological mechanisms and for operative interventions of ruminant species.

Cephalopod-Mimetic Tunable Photonic Coatings Assembled from Quasi-Monodispersed Reflectin Protein Nanoparticles

The remarkable dynamic camouflage ability of cephalopods arises from precisely orchestrated structural changes within their chromatophores and iridophores photonic cells. This mesmerizing color display remains unmatched in synthetic coatings and is regulated by swelling/deswelling of reflectin protein nanoparticles, which alters platelet dimensions in iridophores to control photonic patterns according to Bragg's law. Toward mimicking the photonic response of squid's skin, reflectin proteins from Sepioteuthis lessioniana were sequenced, recombinantly expressed, and self-assembled into spherical nanoparticles by conjugating reflectin B1 with a click chemistry ligand. These quasi-monodisperse nanoparticles can be tuned to any desired size in the 170-1000 nm range. Using Langmuir-Schaefer and drop-cast deposition methods, ligand-conjugated reflectin B1 nanoparticles were immobilized onto azide-functionalized substrates via click chemistry to produce monolayer amorphous photonic structures with tunable structural colors based on average particle size, paving the way for the fabrication of eco-friendly, bioinspired color-changing coatings that mimic cephalopods' dynamic camouflage.

Outer retinal thickness and visibility of the choriocapillaris in four distinct retinal regions imaged with spectral domain optical coherence tomography in dogs and cats

PURPOSE

To evaluate the outer retinal band thickness and choriocapillaris (CC) visibility in four distinct retinal regions in dogs and cats imaged with spectral domain optical coherence tomography (SD-OCT). To attempt delineation of a fovea-like region in canine and feline SD-OCT scans, aided by the identification of outer retinal thickness differences between retinal regions.

METHODS

Spectralis® HRA + OCT SD-OCT scans from healthy, anesthetized dogs (n = 10) and cats (n = 12) were analyzed. Scanlines on which the CC was identifiable were counted and CC visibility was scored. Outer nuclear layer (ONL) thickness and the distances from external limiting membrane (ELM) to retinal pigment epithelium/Bruch's membrane complex (RPE/BM) and ELM to CC were measured in the area centralis (AC), a visually identified fovea-like region, and in regions superior and inferior to the optic nerve head (ONH). Measurements were analyzed using a multilevel regression.

RESULTS

The CC was visible in over 90% of scanlines from dogs and cats. The ONL was consistently thinnest in the fovea-like region. The outer retina (ELM-RPE and ELM-CC) was thickest within the AC compared with superior and inferior to the ONH in dogs and cats (p < .001 for all comparisons).

CONCLUSIONS

The CC appears a valid, albeit less than ideal outer retinal boundary marker in tapetal species. The AC can be objectively differentiated from the surrounding retina on SD-OCT images of dogs and cats; a fovea-like region was identified in dogs and its presence was suggested in cats. These findings allow targeted imaging and image evaluation of these regions of retinal specialization.

Morphology and Histology of the Orbital Region and Eye of the Asiatic Black Bear (Ursus thibetanus)—Similarities and Differences within the Caniformia Suborder

In this study, we present first data concerning the morphological observations of the orbital region, eye tunics, upper and lower eyelids, superficial gland of the third eyelid with the third eyelid, and lacrimal gland in captive adult male Asiatic black bear. The following research methods were used in the work: the eyeball morphometry, the orbital region description, macroscopic description, morphometric and histological analysis of the eye tunics and selected the accessory organs of the eye (Fontana–Masson, hematoxylin & eosin (H&E), Methyl-green-pyronin Y (MGP Y), Movat pentachrome, and picro-Mallory trichrome) as well as histochemical examination (PAS, AB pH 1.0, AB pH 2.5, AB pH 2.5/PAS and HDI). The eyeball of the Asiatic black bear was a spherical shape, while the periorbita was funnel/conical-shaped and the eye socket was of the open type. The cornea was absent of the Bowman’s membrane similar to all domestic dogs and some wild dogs. There were palisades of Vogt in the corneal limbus epithelium similar to the Canidae. Degenerative choroidal tapetum lucidum similar to ranch mink (Mustelidae) has been found. The pupil was big and round in shape. The ciliary muscle, dilatator and sphincter muscle were well developed, similar to the pinnipeds. The lens was biconvex round, similar to the Canidae. The retina was composed similarly to the diurnal terrestrial carnivores. In both eyelids were observed very well-developed tarsal glands, ciliary glands and sebaceous glands. The orbital zone in the eyelids was characterized by lymphoid follicles, diffuse lymphocytes and specialized high endothelial venules. In the anterior palpebral margin of the upper eyelid, soft and short eyelashes were observed, while in the lower eyelids they were absent. The third eyelid was T-shaped and composed of the hyaline tissue, and it contained CALT, similar to that in Canidae. The superficial gland of the third eyelid was a multilobar alveolar branched complex with seromucous nature, while the lacrimal gland was also a multilobar acinar branched complex gland, but producing a mucous–serous secretion. The results of our research indicate that the features of the anatomy of the eye and orbital region in Asiatic black bear are also typical of the Ursidae family. Moreover, a detailed analysis of the morphological eye region may be useful in comparative studies and veterinary diagnostics in this bear species.

Evolving Patterns of Hyperfluorescent Fundus Autofluorescence Accompany Retinal Atrophy in the Rat and Mimic Atrophic Age-Related Macular Degeneration

Purpose

Complex two-dimensional (2D) patterns of hyperfluorescent short-wave fundus autofluorescence (FAF) at the border of geographic atrophy (GA) can predict its expansion in patients with late non-exudative “dry” AMD. However, preclinical models do not phenocopy this important feature of disease. We sought to describe the spatiotemporal changes in hyperfluorescent FAF patterns that occur following acute oxidative stress, potentially in association with GA expansion.

Methods

Sprague Dawley rats (n = 54) received systemic sodium iodate (25–45 mg/kg, n = 90 eyes) or saline (n = 18 eyes) and underwent serial full fundus imaging by confocal scanning laser ophthalmoscopy, including blue FAF and delayed near-infrared analysis. Composite images of the fundus were assembled, and the 2D patterns were described qualitatively and quantitatively. A subset of eyes underwent tissue analysis, and four underwent optical coherence tomography (OCT) imaging.

Results

Reproducibly changing, complex patterns of hyperfluorescent FAF emerge at the borders of toxin-induced damage; however, in the absence of GA expansion, they percolate inward within the region of retinal pigment epithelium loss, evolving, maturing, and senescing in situ over time. Unexpectedly, the late FAF patterns most closely resemble the diffuse tricking form of clinical disease. A five-stage classification system is presented.

Conclusions

Longitudinal, full-fundus imaging of outer retinal atrophy in the rat eye identifies evolving, complex patterns of hyperfluorescent FAF that phenocopy aspects of disease.

Translational Relevance

This work provides a novel tool to assess hyperfluorescent FAF in association with progressive retinal atrophy, a therapeutic target in late AMD.

Morphological evaluation of the orbit, eye tunics, eyelids, and orbital glands in young and adult aardvarks Orycteropus afer, Pallas, 1766 (Tubulidentata: Orycteropodidae) - similarities and differences with representatives of the Afrotheria clade

The Afrotheria clade includes a large group of extant mammals, and the aardvark (Orycteropus afer) is the only representative of the order Tubulidentata in it. Here, we studied the morphological nature of the orbital region, eye tunics, upper and lower eyelids, superficial gland of the third eyelid, the third eyelid, deep gland of the third eyelid, and lacrimal gland in post-mortem specimens obtained from three captive aardvarks, two young and one adult. The obtained samples were analyzed using macroscopic, histological, and histochemical methods. We observed choroidal tapetum lucidum fibrosum in all specimens, which was typical for aardvarks. The superficial gland of the third eyelid was a compound multilobar tubular branched gland of a mucous nature. The deep gland of the third eyelid produced a serous secretion. The seromucous secretion was typical for the lacrimal gland. We compared the morphological data of the O. afer skull with that from other endemic African mammals in the Afrotheria clade. We found that other authors provided different anatomical names for some bones and foramina located within the orbit. The types and function of eyelid glands, as well as eyeball glands of aardvarks, can primarily be connected with their habitat. Our study may constitute an introduction to the ontogenesis of individual eyeball glands in aardvarks. This article is protected by copyright. All rights reserved.

Carried away by a moonlight shadow: activity of wild boar in relation to nocturnal light intensity

An increase of nocturnal activity of ungulate species may represent a compensatory opportunity for energy intake, when activity in daylight is hindered by some disturbance events (e.g. hunting or predation). Therefore, mostly-diurnal and crepuscular species may be active in bright moonlight nights whereas others may shift their diurnal activity towards darkest nights to limit their exposure to predators. In natural and undisturbed conditions, the wild boar may be active both during the day and the night, with alternating periods of activity and resting. In this work, we tested whether activity patterns of wild boar, a species with poor visive abilities, were dependent on moon phases and environmental lightening. We aimed to assess if nocturnal activity could be better explained by variations of the lunar cycle or by the variations of environmental lightening conditions, evaluated by means of different measures of night brightness. Data were collected through camera-trapping in Central Italy in 2019–2020. Despite the poor visive abilities of the wild boar, we observed that this ungulate significantly reduced their activity by avoiding the brightest nights. In our study area, the wild boar has to cope with both human pressure (i.e. mostly hunters and poachers) and predation by the grey wolf. Furthermore, the nocturnal activity of wild boar peaked in mid-Autumn, i.e. when hunting pressure is the highest and when leaf fall may bring wild boar to range for long distances to find suitable resting sites for diurnal hours.

Bat point counts: A novel sampling method shines light on flying bat communities

Emerging technologies based on the detection of electro-magnetic energy offer promising opportunities for sampling biodiversity. We exploit their potential by showing here how they can be used in bat point counts-a novel method to sample flying bats-to overcome shortcomings of traditional sampling methods, and to maximize sampling coverage and taxonomic resolution of this elusive taxon with minimal sampling bias. We conducted bat point counts with a sampling rig combining a thermal scope to detect bats, an ultrasound recorder to obtain echolocation calls, and a near-infrared camera to capture bat morphology. We identified bats with a dedicated identification key combining acoustic and morphological features, and compared bat point counts with the standard bat sampling methods of mist-netting and automated ultrasound recording in three oil palm plantation sites in Indonesia, over nine survey nights. Based on rarefaction and extrapolation sampling curves, bat point counts were similarly effective but more time-efficient than the established methods for sampling the oil palm species pool in our study. Point counts sampled species that tend to avoid nets and those that are not echolocating, and thus cannot be detected acoustically. We identified some bat sonotypes with near-infrared imagery, and bat point counts revealed strong sampling biases in previous studies using capture-based methods, suggesting similar biases in other regions might exist. Our method should be tested in a wider range of habitats and regions to assess its performance. However, while capture-based methods allow to identify bats with absolute and internal morphometry, and unattended ultrasound recorders can effectively sample echolocating bats, bat point counts are a promising, non-invasive, and potentially competitive new tool for sampling all flying bats without bias and observing their behavior in the wild.

Ocular microscopy of Bradypus variegatus

Bradypus variegatus, popularly known as common sloth or brown-throated sloth, is a species with wide geographical distribution in Brazil. Expand on the literature about the species, we aimed to describe the morphology of its eye and its main annexes. For this study, six frozen specimens donated to the Animal Morphological Research Laboratory of the Federal Rural University of Amazonia were used. The specimens were fixed in a 10% aqueous solution of formaldehyde. The structures that constitute the ocular apparatus were identified and described after dissection and histological analysis using light microscopy. The bulbar conjunctiva presented a stratified cuboidal epithelium, with a considerable number of serous glands. The stroma layer and the posterior limiting lamina were found well defined in the species. The corneoscleral meshwork possessed a large opening for drainage of aqueous humour, followed by a wide retinal region, in which a layer of photoreceptors was visualized. Cones and rods could not be discriminated from each other. Microscopy of the medial angle of the eye revealed the cartilage and glands of the third eyelid, and a well-developed lacrimal gland structure. Bradypus variegatus distinguishing features and similarities in comparison with other domestic and wild mammal and bird species already described were investigated, which expounded the limited knowledge that is presently available on the morphology of wild fauna. The data extend the limited knowledge that are presently available on the ocular histology of B. variegatus.

β-Cleavage of the prion protein in the human eye: Implications for the spread of infectious prions and human ocular disorders

Recently, we reported β-cleavage of the prion protein (PrP^C) in human ocular tissues. Here, we explored whether this is unique to the human eye, and its functional implications. A comparison of the cleavage pattern of PrP^C in human ocular tissues with common nocturnal and diurnal animals revealed mainly β-cleavage in humans, and mostly full-length PrP^C in animal retinas. Soluble FL PrP^C and N-terminal fragment (N2) released from β-cleavage was observed in the aqueous and vitreous humor (AH & VH). Expression of human PrP^C in ARPE-19 cells, a human retinal pigmented epithelial cell line, also showed β-cleaved PrP^C. Surprisingly, β-cleavage was not altered by a variety of insults, including oxidative stress, suggesting a unique role of this cleavage in the human eye. It is likely that β-cleaved C- or N-terminal fragments of PrP^C protect from various insults unique to the human eye. On the contrary, β-cleaved C-terminus of PrP^C is susceptible to conversion to the pathological PrP-scrapie form, and includes the binding sites for β1-integrin and amyloid-β, molecules implicated in several ocular disorders. Considering the species and tissue-specific cleavage of PrP^C, our data suggest re-evaluation of prion infectivity and other ocular disorders of the human eye conducted in mouse models.

Visual adaptation and retinal characterization of the Garganey (Anas querquedula): Histological and scanning electron microscope observations

The present study was designed to provide a complete morphological description of the eye of the migratory Garganey duck (Anas querquedula) and its visual adaptation with the different surrounding environmental conditions during its migration journeys using a stereomicroscope, scanning electron microscope (SEM), and light microscope. The current work depends on six adult Garganey ducks that were captured from the area near and on the shores of Edku city. The obtained results revealed that the eye of the migratory Garganey duck has the features of both diurnal and nocturnal birds. The histological examination reveals that the pigmented epithelium of the retina has long prolongations filled with melanin. The cone is the dominant photoreceptor, but simple rods are present. The inner nuclear and ganglion cell layers are thick. SEM examination shows that the arrangement of the collagen fibrils on the external surface was reticular in shape. The radial folds present as pledged structures on the pigmented epithelium covered with circular structures. The main lens body has flat with hexagonal outlines fibers. The edges and surfaces of these hexagonal fibers were studded with protrusions or elevations (balls) and depressions (sockets). The sockets and balls were either rounded or ellipsoid in shape. The balls were more on the edges and the sockets on the surface. In conclusion, our findings indicated a higher degree of functional adaptation between the morphological structure of the eye and the surrounding environmental conditions.

Cochlear hair cells of echolocating bats are immune to intense noise

Exposure to intense noise can damage cochlear hair cells, leading to hearing loss in mammals. To avoid this constraint, most mammals have evolved in relatively quiet environments. Echolocating bats, however, are naturally exposed to continuous intense sounds from their own and neighboring sonar emissions for maintaining sonar directionality and range. Here, we propose the presence of intense noise resistance in cochlear hair cells of echolocating bats against noise-induced hearing loss (NIHL). To test this hypothesis, we performed noise exposure experiments for laboratory mice, one nonecholocating bat species, and five echolocating bat species. Contrary to nonecholocating fruit bats and mice, the hearing and the cochlear hair cells of echolocating bats remained unimpaired after continuous intense noise exposure. The comparative analyses of cochleae transcriptomic data showed that several genes protecting cochlear hair cells from intense sounds were overexpressed in echolocating bats. Particularly, the experimental examinations revealed that ISL1 overexpression significantly improved the survival of cochlear hair cells. Our findings support the existence of protective effects in cochlear hair cells of echolocating bats against intense noises, which provides new insight into understanding the relationship between cochlear hair cells and intense noises, and preventing or ameliorating NIHL in mammals.

Canine Special Senses: Considerations in Olfaction, Vision, and Audition

Canine companions have learned to aid in performing tasks and conducting work for decades. Areas where unique capabilities of working dogs are harnessed are growing. This expansion, alongside efforts to increase domestic purpose-bred stock and awareness of the important role working dogs play in society, is increasing the role veterinarians provide. This article provides a brief overview of 3 key sensory systems in working dogs and highlights considerations for care related to each olfaction, audition, and vision.

Multimodal cues facilitate ripe-fruit localization and extraction in free-ranging pteropodid bats

Sensory cues play an important role in any plant-animal interaction. Yet, we know very little about the cues used by wild mammals during fruit selection. Existing evidence mainly comes from captive studies and suggests that the pteropodid bats rely on olfaction to find fruits. In this study, we avoided captivity-generated stressors and provide insights from natural selective forces by performing manipulative experiments on free-ranging fruit bats (Cynopterus sphinx) in a wild setting, in a tree species that exhibits a bat-fruit syndrome (Madhuca longifolia var. latifolia). We find that visual cues are necessary and sufficient to locate ripe fruits. Fruit experiments exhibiting visual cues alone received more bat visits than those exhibiting other combinations of visual and olfactory cues. Ripe fruit extractions were higher by bats that evaluated fruits by perching than hovering, indicating an additional cue, i.e., haptic cue. Visual cues appear to be informative over short distances, whereas olfactory and haptic cues facilitate the fruit evaluation for those bats that used hovering and perching strategies, respectively. This study also shows that adult bats were more skillful in extracting ripe fruits than the young bats, and there was a positive correlation between the weight of selected fruits and bat weight. This study suggests that the integration of multimodal cues (visual, olfactory and haptic) facilitate ripe-fruit localization and extraction in free-ranging pteropodid bats.

Anatomical and morphometric evaluation of the orbit, eye tunics, eyelids and orbital glands of the captive females of the South African painted dog (Lycaon pictus pictus Temminck, 1820) (Caniformia: Canidae)

In this study, we present the first data concerning the anatomical, morphometrical, histological and histochemical study of the orbit, eye tunics, eyelids and orbital glands in South African Painted Dogs (Lycaon pictus pictus). The study was performed using eyeball morphometry, analysis of the bony orbit including its morphometry, macroscopic study, morphometry, histological examination of the eye tunics and chosen accessory organs of the eye and histochemical analysis. The orbit was funnel shaped and was open-type. There was a single ethmoid opening for the ethmoid nerve on the orbital lamina. The pupil was round, while the ciliary body occupied a relatively wide zone. The iris was brown and retina had a pigmented area. The cellular tapetum lucidum was semi-circular and milky and was composed of 14-17 layers of tapetal cells arranged in a bricklike structure. In the lower eyelid, there was a single conjunctival lymph nodule aggregate. One or two additional large conjunctval folds were observed within the posterior surface of the upper eyelids. The superficial gland of the third eyelid had a serous nature. The third eyelid was T-shaped and was composed of hyaline tissue. Two to three conjunctival lymph nodul aggregates were present within the bulbar conjunctiva of the third eyelid. The lacrimal gland produced a sero-mucous secretion. A detailed anatomic analysis of the eye area in the captive South African Painted Dogs females showed the similarities (especially in the histological examination of the eyetunics and orbital glands) as well as the differences between the Painted dog and the other representatives of Canidae. The differences included the shape and size od the orbita with comparison to the domestic dog. Such differences in the orbit measurements are most likely associated with the skull type, which are defined in relation to domestic dogs. The presented results significantly expand the existing knowledge on comparative anatomy in the orbit, eye and chosen accessory organs in wild Canidae.

Research Relevant Background Lesions and Conditions: Ferrets, Dogs, Swine, Sheep, and Goats

Animal models provide a valuable tool and resource for biomedical researchers as they investigate biological processes, disease pathogenesis, novel therapies, and toxicologic studies. Interpretation of animal model data requires knowledge not only of the processes/diseases being studied but also awareness of spontaneous conditions and background lesions in the model that can influence or even confound the study results. Species, breed/stock, sex, age, anatomy, physiology, diseases (noninfectious and infectious), and neoplastic processes are model features that can impact the results as well as study interpretation. Here, we review these features in several common laboratory animal species, including ferret, dog (beagle), pig, sheep, and goats.

CLINICAL OPHTHALMIC PARAMETERS OF THE TEXAS TORTOISE (GOPHERUS BERLANDIERI)

Ophthalmic studies of the Texas tortoise (Gopherus berlandieri) established normal ophthalmic parameters for select diagnostic tests in captive tortoises and assessment of differences among individuals of differing size and health status. Sixty-one tortoises of varying weight, shell size, Mycoplasma seroprevalence, and herpesvirus exposure were included. Complete ophthalmic examinations, including neuro-ophthalmic reflexes, phenol red thread test, rebound tonometry, fluorescein staining, palpebral fissure length measurement, slit lamp biomicroscopy, indirect fundoscopy, and ocular ultrasound measurements of axial globe length, anterior chamber depth, lens thickness, and vitreous length, were recorded. All tortoises had negative dazzle and pupillary light reflexes, inconsistent menace responses, and positive palpebral reflexes. Mean ± SD tear production and intraocular pressure (IOP) were 14.2 ± 5.6 mm/15 sec and 13.8 ± 2.4 mm Hg in healthy tortoises, respectively. Mycoplasma-seropositive tortoises (with or without herpesvirus exposure) had significantly increased tear production (20.2 ± 8.1 and 19.9 ± 8.9 mm/15 sec, respectively) compared with healthy seronegative tortoises (14.2 ± 5.6 mm/15 sec; P = 0.02). As body size decreased, so too did palpebral fissure length and ocular ultrasound measurements, while IOP increased. Overall, palpebral fissure length appeared relatively small, and tear production relatively increased compared with other chelonian species, likely on the basis of the relatively arid native habitat. Further work is recommended to establish baseline values in related species, as well as comparison in aquatic versus terrestrial chelonians. The authors further suggest that the finding of relatively increased tear production in tortoises may indicate the need to rule out mycoplasmosis as a cause of upper respiratory tract disease.

Ocular examination findings and measurements of tear production and tonometry of ring-tailed coatis (nasua nasua)

OBJECTIVE

To describe ocular anatomical features and to determine tear production and tonometry in normal anesthetized ring-tailed coati (Nasua nasua).

ANIMALS

Eight male and seven female ring-tailed coatis (30 eyes) were evaluated, with ages ranging from 7 months to 10 years old.

PROCEDURES

The animals were anesthetized with isoflurane and had STT 1, rebound and applanation tonometry, and palpebral fissure length (PFL) measured in both eyes. Rebound tonometry was measured with both TonoVet® and TonoVet Plus®. All eyes were evaluated with slit-lamp biomicroscopy. Following pharmacological mydriasis, direct fundoscopy was performed. ANOVA and Tukey tests were used for the data analysis.

RESULTS

There were upper and lower eyelids, as well as a third eyelid. Eyelashes were present on the upper eyelid, while meibomian glands openings were visible on both. The bulbar conjunctiva was pigmented. The pupil was obliquely horizontally ovoid and teardrop shaped when miotic. The color of the iris and tapetum lucidum varied with age. The optic disk was round, and the retina was holangiotic. The mean ± standard deviation values obtained were as follows: STT: 2.50 ± 2.39 mm/min; rebound tonometry: 9.50 ± 2.43 mmHg (TonoVet®, calibration P), 14.60 ± 2.82 mmHg (TonoVet®, calibration D), 18.93 ± 3.99 mmHg (TonoVet Plus®, calibration dog); applanation tonometry: 18.66 ± 4.16 mmHg; PFL: 10.98 ± 1.67 mm.

CONCLUSIONS AND CLINICAL RELEVANCE

Anatomical and clinical ophthalmic data presented in this study are unprecedented for this species. The results can be used as clinical reference parameters, allowing for better care of these species. The lack of data for the Procyonidae family must be regarded as an incentive for more studies.

Mammalian Retinal Cell Quantification

Normal retina and its cell layers are essential for processing visual stimuli, and loss of its integrity has been documented in many disease processes. The numbers and the axonal processes of retinal ganglion cells are reduced substantially in glaucoma, leading to vision loss and blindness. Similarly, selective loss of photoreceptors in age-related macular degeneration and hereditary retinal dystrophies also results in the compromise of visual acuity. Development of genetically modified mice has led to increased understanding of the pathogenesis of many retinal diseases. Similarly, in this digital era, usage of modalities to quantify the retinal cell loss has grown exponentially leading to a better understanding of the suitability of animal models to study human retinal diseases. These quantification modalities provide valuable quantifiable data in studying pathogenesis and disease progression. This review will discuss the immunohistochemical markers for various retinal cells, available automated tools to quantify retinal cells, and present an example of retinal ganglion cell quantification using HALO image analysis platform. Additionally, we briefly review retinal cell types and subtypes, salient features of retina in various laboratory animal species, and a few of the main disease processes that affect retinal cell numbers in humans.

The fine structure of the turbot eye (Scophtalmus maximus): A macro-anatomical, light and scanning electron microscopical study

In fish species, the morphological structure of the eye varies depending on environmental conditions. Morphometric data about the sensory organs of fish is lacking. Therefore, this study aims to describe the morphological structure of the turbot eye using gross, light and scanning electron microscope examinations. The turbot eyeball was found to comprise three layers: the tunica fibrosa bulbi (cornea, sclera), the tunica vasculosa bulbi (choroidea, iris) and the tunica nervea bulbi (retina). The thickness of the centre of the cornea measured approximately 153.14 μm, and the peripheral thickness measured 410.81 μm. The sclera consisted of a two-part cartilage structure that was connected with elastic fibres. The choroideal rete was found in the tunica vasculosa bulbi, and its thickness measured 1.6 ± 0.1 mm. Moreover, no pigment was found in the choroidea. The lens was determined to be a very hard and transparent structure extending towards the cornea. In addition, we detected five ligaments in the equatorial plane of the eye, in which the tendon of the retractor lentis muscle attaches to the lens. Also, there were six extraocular muscles in the turbot. This study is the first to present detailed descriptions of morphological structures and morphometric data for all the layers of the turbot eye. Since the anatomical structure of the eye in fish is variable, it is thought that the data on the turbot eye will contribute to the anatomy literature.