Characterization of ocular gland morphology and tear composition of pinnipeds

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.

Histological and histochemical characteristics of lacrimal glands in beluga whales (Delphinapterus leucas)

The objective of this study was to describe the histological and histochemical characteristics of the lacrimal glands of beluga whales. The study was carried out on the formalin-fixed ocular globes from 96 carcasses of beluga whales found stranded in the St. Lawrence estuary in Quebec, Canada. Hematoxylin and eosin (H&E) stained slides from the eyes of each whale were examined for lacrimal glands. Histological description was done with H&E and Masson Trichrome (MT) stains. Period Acid-Schiff (PAS), Alcian blue (AB) pH 1.0 and 2.5, and High Iron Diamine (HID) stains were used for histochemical characterization of glycoproteins. Thirteen ocular samples from animals ranging from neonate to 48 y included sections of lacrimal glands. The H&E stain revealed a tubuloalveolar gland architecture, separated into lobules by dense connective tissue. Each lobule contained a mixture of acini and tubules with ductules. Small and large acini were composed of low and tall columnar cells, respectively. Acinar cells contained basophilic cytoplasmic granules. The ductules were lined with a bi-layered cuboidal-to-squamous epithelium. The MT stain highlighted the connective tissue separating ductules and acini. Large acini were positive for PAS and some small acini had patchy uptake. Positive staining for AB pH 1.0 and 2.5 was mainly seen in tall columnar cells as compared to small acini that had faint to no stain uptake. High Iron Diamine stain revealed 90% staining of all acinar cells, with 10% exhibiting a mixed blue-black tinge. It was concluded that the lacrimal glands of beluga whales have similar histological and histochemical findings to those of artiodactyla and carnivora orders.

Iris-like eye closure of the fine-patterned pufferfish, Takifugu flavipterus

Unlike many tetrapods and elasmobranchs, eye-closing ability is absent in bony fishes, with the single-known exception of the family Tetraodontidae. We observed the eye-closing response of the tetraodontid fine-patterned puffer, Takifugu flavipterus, which provides the first detailed data on the kinematics and mechanism of this ability in this family. During eye-closing behavior, the skin around the eye converges toward the center of the iris. This is very different to the reversing uni-directional (e.g., upward then downward) movement of the eyelids of other vertebrates. Electrical stimulation of a freshly dead specimen showed that this movement occurs due to the contraction of a sheet of muscle located just beneath the skin around the eye, which is characteristic of Family Tetraodontidae. Eye-closing is accompanied by simultaneous retraction of the eyeball away from the surface, which is initiated just before the skin of the eye begins to move. The eye-closing ability observed in this study appears to have been acquired independently in the Tetraodontidae.

Comparative Analysis of Tear Composition in Humans, Domestic Mammals, Reptiles, and Birds

Tears are an important component of the ocular surface protection mechanism and are in close contact with the corneal epithelium and the environment. Their composition is well-known in humans; however, there are few investigations on the composition and function of tears in reptiles, birds and others mammals, which would elucidate the mechanisms governing the maintenance of ocular homeostasis. In this work, electrophoretic profiles and an evaluation of total protein, albumin, urea, glucose, and cholesterol concentrations in tears of semi-aquatic, terrestrial, and marine reptiles (Caiman latirostris, Chelonia mydas, Caretta caretta, Eretmochelys imbricata, Lepidochelys olivacea, and Chelonoidis carbonaria), birds (Tyto furcata, Rupornis magnirostris and Ara ararauna), and mammals (Equus caballus and Canis lupus familiaris) were apresented. Human tear components and respective blood serum samples were used as references. The electrophoretic analysis revealed similarities whithin same Classes. The results of the tear-blood serum relationship and the comparison to human tear components showed particularities that are potentially derived from a homeostatic response to the environment. When the tear compositions of animals belonging to different ecological clusters were compared, marked differences were observed in total protein and urea concentrations. Thus, reptile, bird, and mammalian tears are complex fluids with differing concentrations of biochemical components that are potentially a result of the animals' adaptation to different environments.

Ocular Surface Diseases in Marine Mammals

Marine mammal eyes are adapted for underwater and air environments by increasing the mucins in tear film and having flatter corneas and round crystalline lenses. The cornea and lens are most commonly affected by environmental imbalances. Lack of shade and excessive exposure to sunlight are significant risk factors for keratopathy in pinnipeds, and likely true in cetaceans. Natural aging is also important, as sun damage and exposure to other oxidative stressors can cause cumulative damage to the cornea over time. By diminishing UV exposure and optimizing environmental factors, surface ocular disease in marine mammals can be diminished.

Evaluation of lacrimal production, osmolarity, crystallization, proteomic profile, and biochemistry of capuchin monkeys' tear film

BACKGROUND

To evaluate the composition and characteristics of capuchin monkey (CM) tear film.

METHODS

Eleven CM (Sapajus sp.) was evaluated. Strip meniscometry test (SMT), osmolarity, and tear ferning test (TFT) (by Rolando and Masmali scales) were assessed. Tear protein profile (SDS-PAGE), and total protein, albumin, urea, glucose, and cholesterol levels in tear film and blood serum were screened.

RESULTS

Median ± semi-interquatil range for SMT and osmolarity values were 8.0 ± 1.625 and 303.0 ± 9.875, respectively. TFT for Rolando was 2.0 ± 0.5, and Masmali was 2.0 ± 0.0. Monkeys's tear obtained type II and III for Rolando, and 1 and 2 for Masmali. Tear components showed protein bands among 23-217 kDa, and presence of albumin, urea, glucose, and cholesterol.

CONCLUSIONS

The results of SMT, osmolarity, TFT, SDS-PAGE, and tear biochemistry may serve as a reference baseline for CM, and the data may serve as a basis for future experimental model evaluations.

Conjunctival bacterial flora and antimicrobial susceptibility of captive and free-living sea turtles in Brazil

PURPOSE

To describe the aerobic conjunctival bacterial flora of 3 especies of free-living and under human care sea turtles and determine its antimicrobial susceptibility in vitro.

METHOD

Thirty-six sea turtles (72 eyes), juveniles and adults, 7 free-living Chelonia mydas and 8 Chelonia mydas, 4 Caretta caretta, 11 Eretmochelys imbricata, and 6 Lepidochelys olivacea under human care, were evaluated. Conjunctival cultures were collected for identification of aerobic bacteria and antimicrobial susceptibility testing for ciprofloxacin, chloramphenicol, gentamicin, neomycin, oxacillin, polymyxin B, tetracycline, and tobramycin using antibiotic disks. Bacterial strains showing no sensitivity to 4 or more antimicrobials were considered multiresistant to this panel.

RESULTS

Bacterial growth was observed in 12/14 (85.71%) samples in the free-living sea turtles, and there was growth in 100% (58/58) of the samples from captive animals. There were 94 strains isolated and 15 species identified. There was a predominance of Gram-positive bacteria in free-living Chelonia mydas, most of which were Bacillus and Staphylococcus. The most commonly isolated Gram-negative species were enterobacteria for free-living and under human care animals. The strains were predominantly sensitive to ciprofloxacin and tobramycin, and less sensitive to oxacillin or polymyxin B. Ten multiresistant strains were isolated. Yeast were identified in 13.89% (10/72) of the samples.

CONCLUSIONS

These results, showing differences in the conjunctival bacterial flora of free-living and captive animals, may be helpful for diagnosis and treatment of ocular disorders in sea turtles.

Ontogeny of the Orbital Glands and Their Environs in the Pantropical Spotted Dolphin (Stenella attenuata: Delphinidae)

The nasolacrimal duct (NLD) connects the orbital (often associated with the Deep Anterior Orbital gland: DAOG, a.k.a. Harderian gland) and nasal regions in many tetrapods. Adult cetaceans are usually said to lack an NLD, and there is little agreement in the literature concerning the identity of their orbital glands, which may reflect conflicting definitions rather than taxonomic variation. In this study, we examined an embryological series of the pantropical spotted dolphin (Stenella attenuata), and report numerous divergences from other tetrapods. Underdeveloped eyelids and a few ventral orbital glands are present by late Stage (S) 17. By S 19, circumorbital conjunctival glands are present. In S 20, these conjunctival glands have proliferated, eyelids (and scattered palpebral glands) have formed, and a duct similar to the NLD has appeared. Subsequently, both the palpebral glands and the NLD are progressively reduced by S 22, even as the conjunctival glands exhibit regional growth. In most tetrapods examined, the ontogeny of the NLD follows a series of three stages: Inception of NLD, Connection of orbit and nasal cavity by the NLD and Ossification (i.e., formation of the bony canal surrounding the NLD, emerging into the orbit via the lacrimal foramen in the lacrimal bone). In contrast, the dolphin NLD originates at the same time as the lacrimal bone, and a lacrimal foramen fails to develop. The cetacean fossil record shows that a lacrimal foramen was present in the earliest ancestral amphibious, freshwater forms, but was soon lost as the lineage invaded the oceans. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:77-87, 2018. © 2017 Wiley Periodicals, Inc.