Ostrich (Struthio camelus) syrinx morphology and vocal repertoire across postnatal ontogeny and sex: Implications for understanding vocal evolution in birds

Vocal production in birds has been the target of considerable research that mostly has focused on phylogenetically well-nested songbirds. Anatomical descriptions and recordings of many non-songbirds have often only focused on a single ontogenetic stage or sex. While basic morphology of the vocal organ (syrinx) of ostrich (Palaeognathae, Struthio camelus) has been known since the 1800s, descriptions of its vocal repertoire and syrinx anatomy since then have been incomplete or inconsistent. New toolkits now enable detailed qualitative description of internal anatomy and meristic data and allow it to be compared to vocal production. Here we describe the anatomy of the syrinx in Struthio camelus for three post-hatching ontogenetic stages and both an adult male and female utilizing dissection and contrast enhanced X-ray computed tomography (diceCT). We find changes in ring geometry and spacing through ontogeny as well as lateral labia thickness. We document a small unpaired, midline, cartilaginous structure, a "pessuliform process" at the tracheobronchial juncture present throughout ontogeny and in both males and females. Investigation of the vocal repertoire of ostriches across ontogeny using a new dataset of 77 recordings led to identification of four vocalizations not previously reported in the literature, including the simultaneous production of a hiss and tonal. We find syrinx morphology largely consistent across ontogeny and in male and female adults. Both are capable of producing long duration tonal calls, but these may be more frequent in male birds. Closed-mouth boom calls remain unique to males. A detailed understanding of diversity in parts of early diverging clades is pivotal in attempting to estimate features of the ancestral syrinx in birds and how avian vocalization evolved.

Soft tissues influence nasal airflow in diapsids: Implications for dinosaurs

The nasal passage performs multiple functions in amniotes, including olfaction and thermoregulation. These functions would have been present in extinct animals as well. However, fossils preserve only low-resolution versions of the nasal passage due to loss of soft-tissue structures after death. To test the effects of these lower resolution models on interpretations of nasal physiology, we performed a broadly comparative analysis of the nasal passages in extant diapsid representatives, e.g., alligator, turkey, ostrich, iguana, and a monitor lizard. Using computational fluid dynamics, we simulated airflow through 3D reconstructed models of the different nasal passages and compared these soft-tissue-bounded results to similar analyses of the same airways under the lower-resolution limits imposed by fossilization. Airflow patterns in these bony-bounded airways were more homogeneous and slower flowing than those of their soft-tissue counterparts. These data indicate that bony-bounded airway reconstructions of extinct animal nasal passages are far too conservative and place overly restrictive physiological limitations on extinct species. In spite of the diverse array of nasal passage shapes, distinct similarities in airflow were observed, including consistent areas of nasal passage constriction such as the junction of the olfactory region and main airway. These nasal constrictions can reasonably be inferred to have been present in extinct taxa such as dinosaurs.

Study on bio-inspired feet based on the cushioning and shock absorption characteristics of the ostrich foot

As the main actuator of high-speed running, the ostrich feet are highly capable of cushioning and shock absorption. In this study, based on the elastic modulus scales and assembly order of the 3rd toe soft tissues and the functions of the metatarsophalangeal (MTP) joint, we designed fourteen bio-inspired feet. The impact process on loose sand was simulated on the finite element software Abaqus. Also the stress distributions and deformations of each component of the bio-inspired feet were clarified. With the peak acceleration as the index, the cushioning performances of the bio-inspired feet were compared on both loose sand and solid ground through height-variable impact tests. The 15-15-15 HA (hardness unit) bio-inspired foot showed lower peak acceleration and thereby better cushioning performance, but larger deformation, less-uniform stress distribution and thereby lower stability than the 15-35-55 HA bio-inspired foot. In fact, the silicon rubbers with different hardness degrees (which simulate the elasticity modulus scales of the digital cushions, fascia and skin) and the spring mechanism (which simulates the functions of the MTP joint) work as an “integrated system” of cushioning and shock absorption.

Ostrich eggshell bead diameter in the Holocene: Regional variation with the spread of herding in eastern and southern Africa

Despite their ubiquity in Holocene African archaeological assemblages, ostrich eggshell (OES) beads are rarely studied in detail. An exception is in southern Africa, where there is a proposed relationship between OES bead diameter and the arrival of herding ~2000 years before present. In 1987, Leon Jacobson first observed that beads from forager sites in Namibia tended to be smaller than those associated with herder sites. Studies examining bead size around the Western Cape have generally confirmed Jacobson's findings, though the driving forces of the diameter change remain unknown. Since this time, diameter has become an informal way of distinguishing forager and herder assemblages in southern Africa, but no large-scale studies of OES bead variation have been undertaken. Here we present an expanded analysis of Holocene OES bead diameters from southern, and for the first time, eastern Africa. Results reveal distinct patterns in OES bead size over time, reflecting different local dynamics associated with the spread of herding. In southern Africa, OES diameters display low variability and smaller absolute size through time. While larger beads begin to appear <2000 years ago, most beads in our study remained smaller. In contrast, eastern African OES bead diameters are consistently larger over the last 10,000 years and show no appreciable size change with the introduction of herding. Notably, larger beads thought to be associated with herders in southern Africa fall within the range of eastern African beads, indicating a potential connection between these regions in the Late Holocene consistent with genetic findings. Regional differences in bead size are subtle, on the order of millimeters, yet offer a potentially important line of evidence for investigating the spread of herding in sub-Saharan Africa. In order to understand the meaning of these changes, we encourage additional studies of OES bead assemblages and urge researchers to report individual bead diameters, rather than averages by level.

Radiographic Anatomy of the Metatarsophalangeal Joint and Digits of the Ostrich (Struthio camelus)

The aim of this study was to develop a detailed and accessible set of reference images of the normal radiographic anatomy of the digits of the ostrich (Struthio camelus), with emphasis on the metatarsophalangeal joint and its arthrography. The distal excised pelvic limbs of 10 normal ostriches of different ages (ranging from 10 to 365 days of age) obtained from an abattoir were radiographed, and 2 arthrograms were performed. To illustrate the normal radiographic anatomy of the tarsometatarsal bone, 39 images were selected, labelled, and presented along with detailed descriptions and corresponding images of the bony skeleton. These results provide a valuable dataset to assist in understanding the normal anatomy of the ostrich metatarsophalangeal joint and digits and allow comparison of abnormal corresponding structures in clinical cases in ostriches.

The Tarsometatarsus of the Ostrich Struthio camelus: Anatomy, Bone Densities, and Structural Mechanics

Background

The ostrich Struthio camelus reaches the highest speeds of any extant biped, and has been an extraordinary subject for studies of soft-tissue anatomy and dynamics of locomotion. An elongate tarsometatarsus in adult ostriches contributes to their speed. The internal osteology of the tarsometatarsus, and its mechanical response to forces of running, are potentially revealing about ostrich foot function.

Methods/Principal Findings

Computed tomography (CT) reveals anatomy and bone densities in tarsometatarsi of an adult and a young juvenile ostrich. A finite element (FE) model for the adult was constructed with properties of compact and cancellous bone where these respective tissues predominate in the original specimen. The model was subjected to a quasi-static analysis under the midstance ground reaction and muscular forces of a fast run. Anatomy–Metatarsals are divided proximally and distally and unify around a single internal cavity in most adult tarsometatarsus shafts, but the juvenile retains an internal three-part division of metatarsals throughout the element. The juvenile has a sparsely ossified hypotarsus for insertion of the m. fibularis longus, as part of a proximally separate third metatarsal. Bone is denser in all regions of the adult tarsometatarsus, with cancellous bone concentrated at proximal and distal articulations, and highly dense compact bone throughout the shaft. Biomechanics–FE simulations show stress and strain are much greater at midshaft than at force applications, suggesting that shaft bending is the most important stressor of the tarsometatarsus. Contraction of digital flexors, inducing a posterior force at the TMT distal condyles, likely reduces buildup of tensile stresses in the bone by inducing compression at these locations, and counteracts bending loads. Safety factors are high for von Mises stress, consistent with faster running speeds known for ostriches.

Conclusions/Significance

High safety factors suggest that bone densities and anatomy of the ostrich tarsometatarsus confer strength for selectively critical activities, such as fleeing and kicking predators. Anatomical results and FE modeling of the ostrich tarsometatarsus are a useful baseline for testing the structure’s capabilities and constraints for locomotion, through ontogeny and the full step cycle. With this foundation, future analyses can incorporate behaviorally realistic strain rates and distal joint forces, experimental validation, and proximal elements of the ostrich hind limb.

Osteological and Soft-Tissue Evidence for Pneumatization in the Cervical Column of the Ostrich (Struthio camelus) and Observations on the Vertebral Columns of Non-Volant, Semi-Volant and Semi-Aquatic Birds

Postcranial skeletal pneumaticity (PSP) is a condition most notably found in birds, but that is also present in other saurischian dinosaurs and pterosaurs. In birds, skeletal pneumatization occurs where bones are penetrated by pneumatic diverticula, membranous extensions that originate from air sacs that serve in the ventilation of the lung. Key questions that remain to be addressed include further characterizing (1) the skeletal features that can be used to infer the presence/absence and extent of PSP in birds and non-avian dinosaurs, and (2) the association between vertebral laminae and specific components of the avian respiratory system. Previous work has used vertebral features such as pneumatic foramina, fossae, and laminae to identify/infer the presence of air sacs and diverticula, and to discuss the range of possible functions of such features. Here, we tabulate pneumatic features in the vertebral column of 11 avian taxa, including the flightless ratites and selected members of semi-volant and semi-aquatic Neornithes. We investigate the associations of these osteological features with each other and, in the case of Struthio camelus, with the specific presence of pneumatic diverticula. We find that the mere presence of vertebral laminae does not indicate the presence of skeletal pneumaticity, since laminae are not always associated with pneumatic foramina or fossae. Nevertheless, laminae are more strongly developed when adjacent to foramina or fossae. In addition, membranous air sac extensions and adjacent musculature share the same attachment points on the vertebrae, rendering the use of such features for reconstructing respiratory soft tissue features ambiguous. Finally, pneumatic diverticula attach to the margins of laminae, foramina, and/or fossae prior to their intraosseous course. Similarities in PSP distribution among the examined taxa are concordant with their phylogenetic interrelationships. The possible functions of PSP are discussed in brief, based upon variation in the extent of PSP between taxa with differing ecologies.

Functional anatomy of the lacrimal gland in African black ostrich Struthio camelus domesticus in the embryonic and postnatal period

The aim of the present study was morphological and histochemical analysis of the lacrimalgland (LG) in African black ostrich Struthio camelus domesticus in the embryonic and postnatalperiod. Studies were conducted on 50 ostriches aged between the 28th day of incubation until7 months old. Tissue sections were stained with haematoxylin and eosin, Azan trichrome,periodic acid-Schiff, Alcian blue pH 2.5, aldehyde fuchsin and Hale's dialysed iron. The LGin ostrich was classified as a tubulo-acinar type. The primordia of the lobes were determinedin the LG structure on the 28th day of incubation, whilst the weakly visible lobes with aciniand tubules were observed on the 40th day of incubation. Morphometric studies of the LGshowed steady growth, characterised by an increase in both length and width. Histometricmeasurements of lobe size showed little difference between the first, second and third agegroups, whilst in the fourth age group a marked increase in size of lobes was observed.The study showed that, apart from morphological changes, during the growth of the LGthe character of acid mucopolysaccharides changed. Sulphated acid mucopolysaccharideswere indicated, particularly with aldehyde fuchsin (AF) staining in the fourth age group.The Hale's dialysed iron (HDI) staining showed a low concentration of carboxylated acidmucopolysaccharides in the first and second age groups and a higher concentration in thethird and fourth age groups. Periodic acid-Schiff staining (PAS)-positive cells were observedin each age group, but only a small number of cells with a weakly PAS-positive reaction weredemonstrated in the first age group.

An immunohistochemical study of the presence and distribution of neuronal and glial markers in simple testicular cysts in the ostrich (Struthio camelus)

Simple testicular cysts are rare in birds and mammals. However, the condition has recently been reported in the ostrich (Struthio camelus), an economically important farmed bird. The innervation of normal and cryptorchid testes, unlike the simple testicular cysts of birds and mammals, has received considerable attention. This study, therefore, immunohistochemically demonstrates the presence and the general distribution pattern of neuronal and glial markers in the simple intratesticular cyst, and its associated structures, of fourteen adult ostriches using antibodies to neurofilament protein, S-100, neuron-specific enolase and protein gene product 9.5. The LSAB+ Kit(DakoCytomation, Denmark) immunostaining protocol was used in this study. The normal seminiferous peritubular tissue showed few or no immunoreactive nerve fibres. A greater density of neurofilament protein, S-100, neuron-specific enolase and protein gene product 9.5 immunopositive nerve fibres were observed in the tunica albuginea adjacent to the cyst, as well as in the peritubular connective tissue of cystic seminiferous tubules. In addition, the tunica adventitia of blood vessels within the interstitial space of the cystic seminiferous tubules displayed neurofilament protein, S-100 and protein gene product 9.5 immunoreactive nerve fibres of varying intensity and pattern. Protein gene product 9.5 immunostaining was also observed in the multinucleated giant cells of both the normal and the cystic seminiferous tubules. The cystic portion of the testis appears to have a richer innervation than the normal portion of the same testis. The richer innervation of simple testicular cysts in the ostrich is similar to that observed in the cryptorchid testis of mammals.

[Structural organization of anterior corneal epithelium of the African ostrich eye]

This investigation was aimed at the histological study of anterior corneal epithelium (ACE) of adult male ostrich Struthio camelus Linnaeus, 1758 (Struthioniformes). The total thickness of ACE was equal to 48.5+/-1.1 microm. The geometry of epithelial cells was investigated. The basal cells had columnar shape; their average height was equal to 21.4+/-1.8 microm, average width - to 5.94+/-0,45 microm, configuration index was 3.84+/-0,50. The intermediate cells were predominantly ellipsoidal in shape; their average height was equal to 6.2+/-0.3 microm, average width - to 12.0+/-0.8 microm, configuration index was 0.54+/-0,06. The superficial cells were squamous, their average height was equal to 3.8+/-0.3 microm, average width - to 22.4+/-1.7 microm, configuration index was 0.18+/-0.02. Index of flattening of epithelial cells of the superficial layer was 5.8+/-0.5. Negative correlation (r+/-m=-0,72+/-0,13) was detected between the height and the width of the epithelial cells.

A comparative study on the histological structure of the spleen in the ostrich (Struthio camelus), the kestrel (Falco tinnunculus) and the osprey (Pandion haliaetus)

The spleen structurally and functionally belongs to the hematopoietic organs and is also an important component of the reticuloendothelial system, which is known to play a major role in host defense. The histological structure of the spleen was investigated in the ostrich, a non-flying bird, the kestrel, a raptor, and the osprey, a fish-eating bird of prey (fish eagle). For this purpose, Mallory's modified triple stain, methyl green-pyronin and silver stain were used. Germinal centers were not present in the spleen of the osprey. In the spleen of the kestrel, penicillar arterioles and the surrounding lymphoid tissue were markedly dense. Compared to the other two birds, the red and white pulps were clearly distinguishable in the spleen of the ostrich.

"Ostrich sign" indicates bilateral vertebral artery dissection

Vertebral artery dissections (VADs) comprise about 2% of ischemic strokes and can be associated with trauma, chiropractic manipulation, motor vehicle collisions, whiplash, amusement park rides, golfing, and other motion-induced injuries to the neck. We present a case of bilateral extracranial VAD as a complication of conducting an orchestra. To our knowledge, this has not been documented in the literature. Conceivably, vigorous neck twisting in an inexperienced, amateur conductor may place excessive rotational forces upon mobile portions of the verterbral arteries, tear the intima, deposit subintimal blood that extends longitudinally, and cause neck pain and/or posterior fossa ischemic symptoms. Magnetic resonance angiography examinations of axially oriented slices of bilateral VADs resemble the face of an ostrich. This observation is similar to the "puppy sign," in which bilateral internal carotid artery dissections resemble the face of a dog. Craniocervical dissections of either the carotid or vertebral arteries have the potential to form an aneurysm, cause artery-to-artery embolism, or completely occlude the parent artery, resulting in an ischemic stroke. Because bilateral VADs in axial magnetic resonance angiographic sections stand out like the eyes of an ostrich, and because the fast identification of VADs is so critical, we eponymize this image the "ostrich sign."

Macroscopic Features of the Arterial Supply to the Reproductive System of the Male Ostrich (Struthio camelus)

The macroscopic features of the arterial supply to the reproductive system of the male ostrich was studied in 16 pre-pubertal and eight sexually mature and active birds. The left and right cranial renal arteries arise from the aorta, between the cranial divisions of the kidneys. These vessels supply the cranial divisions of the kidneys, the testes, the epididymides and the cranial segments of the ducti deferentia. Accessory testicular arteries which arise directly from the aorta are present in 45.8% of the specimens. They supply the testes and cranial parts of the ducti deferentia. They are variable in number and origin, and four variants are identified. A cranial ureterodeferential branch originates from the cranial renal artery, supplies the cranial portion of the ductus deferens and ureter, and runs caudally to anastomose with the middle renal artery. The sciatic artery arises laterally from the aorta, just caudal to the acetabulum, and gives rise, ventrally, to a common trunk, the common renal artery, which divides into the middle and caudal renal arteries. The middle renal artery gives rise to the middle ureterodeferential branch which supplies the middle part of the ductus deferens and ureter. A few centimetres caudal to the kidney, the aorta terminates in three branches, namely, the left and right internal iliac arteries and the median caudal artery. The internal iliac artery divides into the lateral caudal artery and the pudendal artery; the latter gives off caudal ureterodeferential branches that supply the caudal segments of the ductus deferens and ureter. In addition, the pudendal artery gives off vessels that supply the cloaca, some of which continue to the base of the phallus, where they form an arterial network. In conclusion, the pattern of the blood supply to the reproductive organs of the male ostrich is, in general, similar to that of the domestic fowl and pigeon, although there are a few highlighted distinctive features.

Running in ostriches (Struthio camelus): three-dimensional joint axes alignment and joint kinematics

Although locomotor kinematics in walking and running birds have been examined in studies exploring many biological aspects of bipedalism, these studies have been largely limited to two-dimensional analyses. Incorporating a five-segment, 17 degree-of-freedom (d.f.) kinematic model of the ostrich hind limb developed from anatomical specimens, we quantified the three-dimensional(3-D) joint axis alignment and joint kinematics during running (at ∼3.3 m s–1) in the largest avian biped, the ostrich. Our analysis revealed that the majority of the segment motion during running in the ostrich occurs in flexion/extension. Importantly, however, the alignment of the average flexion/extension helical axes of the knee and ankle are rotated externally to the direction of travel (37° and 21°, respectively) so that pure flexion and extension at the knee will act to adduct and adbuct the tibiotarsus relative to the plane of movement, and pure flexion and extension at the ankle will act to abduct and adduct the tarsometatarsus relative to the plane of movement. This feature of the limb anatomy appears to provide the major lateral (non-sagittal) displacement of the lower limb necessary for steering the swinging limb clear of the stance limb and replaces what would otherwise require greater adduction/abduction and/or internal/external rotation, allowing for less complex joints, musculoskeletal geometry and neuromuscular control. Significant rotation about the joints'non-flexion/extension axes nevertheless occurs over the running stride. In particular, hip abduction and knee internal/external and varus/valgus motion may further facilitate limb clearance during the swing phase, and substantial non-flexion/extension movement at the knee is also observed during stance. Measurement of 3-D segment and joint motion in birds will be aided by the use of functionally determined axes of rotation rather than assumed axes, proving important when interpreting the biomechanics and motor control of avian bipedalism.

Muscle architecture and functional anatomy of the pelvic limb of the ostrich (Struthio camelus)

The functional anatomy of the pelvic limb of the ostrich (Struthio camelus) was investigated in order to assess musculoskeletal specialization related to locomotor performance. The pelvic limbs of ten ostriches were dissected and detailed measurements of all muscle tendon units of the pelvic limb were made, including muscle mass, muscle length, fascicle length, pennation angle, tendon mass and tendon length. From these measurements other muscle properties such as muscle volume, physiological cross-sectional area (PCSA), tendon cross-sectional area, maximum isometric muscle force and tendon stress were derived, using standard relationships and published muscle data. Larger muscles tended to be located more proximally and had longer fascicle lengths and lower pennation angles. This led to an expected proximal to distal reduction in total muscle mass. An exception to this trend was the gastrocnemius muscle, which was found to have the largest volume and PCSA and also had the highest capacity for both force and power production. Generally high-power muscles were located more proximally in the limb, while some small distal muscles (tibialis cranialis and flexor perforatus digiti III), with short fibres, were found to have very high force generation capacities. The greatest proportion of pelvic muscle volume was for the hip extensors, while the highest capacity for force generation was observed in the extensors of the ankle, many of which were also in series with long tendons and thus were functionally suited to elastic energy storage.

Muscle moment arms of pelvic limb muscles of the ostrich (Struthio camelus)

Muscle moment arms were measured for major muscles of the pelvic limb of the ostrich (Struthio camelus) in order to assess specific functional behaviour and to apply this to locomotor performance. Pelvic limbs of six juvenile ostriches were used for this study. The tendon travel technique was used to measure moment arms of 21 muscles at the hip, knee, ankle and metatarsophalangeal joints throughout the ranges of motion observed during level running. Six of the 21 muscles measured were found to have moment arms that did not change with joint angle, whilst the remainder all demonstrated angle-dependent changes for at least one of the joints crossed. Moment arm lengths tended to be longest for the large proximal muscles, whilst the largest relative changes were found for the moment arms of the distal muscles. For muscles where moment arm varied with joint angle: all hip muscles were found to have increasing moment arms with extension of the joint, knee flexors were found to have moment arms that increased with extension, knee extensor moment arms were found to increase with flexion and ankle extensor moment arms increased with extension. The greatest relative changes were observed in the flexors of the metatarsophalangeal joint, for which a three-fold increase in moment arm was observed from flexion to full extension. Changes in muscle moment arm through the range of motion studied appear to optimize muscle function during stance phase, increasing the effective mechanical advantage of these muscles.

Variance components for live weight, body measurements and reproductive traits of pair-mated ostrich females

Estimates of genetic parameters for reproductive traits, live weight and body measurements were obtained using data from a pair-mated ostrich flock at Oudtshoorn in South Africa. Reproductive traits included total egg and chick production, along with hatchability percentage. Live weight, chest circumference and tail circumferences were recorded at the commencement and cessation of breeding. Heritability estimates (h(2)) were 0.23 for egg production, 0.20 for chick production, 0.10 for hatchability, 0.20 to 0.34 for live weight, 0.12 for chest circumference and 0.30 to 0.38 for tail circumference. Female permanent environmental effects (c(2)) amounted to 0.18 for egg production, 0.18 for chick production, 0.21 for hatchability, 0.32 to 0.36 for live weight and 0.23 to 0.32 for chest circumference. Service sire exerted significant effects only on hatchability (0.22) and subsequently chick production (0.09). Genetic correlations of reproductive traits with live weight were low to moderate, variable in sign, and did not differ significantly from zero. Correlations between live weight recorded at the beginning and end of the breeding season were unity for additive genetic and permanent environmental effects. Egg and chick production were highly correlated genetically and phenotypically, with the genetic correlation exceeding the theoretical limit. In unconstrained analyses, hatchability was positively related to chick production, including at the service sire level. Selection gains in the current flock and future generations are likely. No significant adverse relationships were found between live weight, body measurements and reproductive traits.

Flexibility along the neck of the ostrich (Struthio camelus) and consequences for the reconstruction of dinosaurs with extreme neck length

The gross morphology and the flexibility along the neck of the ostrich (Struthio camelus) were examined using fresh tissue as well as neck skeletons. The results of the morphologic studies were compared with results from observations of living ostriches. The investigation was focused on differences in the morphology and the function between different sections of the neck. Additionally, the function of major dorsal neck ligaments was examined, including measurements of force-strain-relations. Comparative studies of giraffes (Giraffa camelopardalis) and camels (Camelus bactrianus) were conducted to find relations between the flexibility along the neck and the general feeding strategy. The examinations revealed that the neck of the ostrich can be divided into four sections with different functions. The first is the atlas-axis-complex which is responsible for torsion. The adjacent cranial section of the neck is flexible in dorsoventral and lateral directions but this part of the neck is usually kept straight at rest and during feeding. Dorsoventral flexibility is highest in the middle section of the neck, whereas the base of the neck is primarily used for lateral excursions of the neck. For giraffes and camels, the posture and utilization of the neck are also reflected in the flexibility of the neck. For all three species, it is possible to reconstruct the pattern of flexibility of the neck by using the neck skeletons alone. Therefore, it appears reasonable to reconstruct the neck utilization and the feeding strategies of dinosaurs with long necks by deriving the flexibility of the neck from preserved vertebrae. For Diplodocus carnegii the neck posture and the feeding strategy were reconstructed. Two neck regions, one around the 9th neck vertebra and the second at the base of the neck, indicate that Diplodocus, like the ostrich, adopted different neck postures. The neck was probably kept very low during feeding. During interruptions of the feeding, e.g., in an alert, the head could have been lifted in an economic way by raising the cranial section of the neck. During standing and locomotion the head was probably located well above the shoulders.

The morphology of the pecten oculi of the ostrich, Struthio camelus

The pecten oculi is a structure peculiar to the avian eye. Three morphological types of pecten oculi are recognized: conical type, vaned type and pleated type. The pleated type has been well studied. However, there exists only scanty data on the morphology of the latter two types of pectens. The structure of the vaned type of pecten of the ostrich, Struthio camelus was investigated with light and electron microscope. The pecten of this species consists of a vertical primary lamella that arises from the optic disc and supports 16-19 laterally located secondary lamellae, which run from the base and confluence at the apex. Some of the secondary lamellae give rise to 2 or 3 tertiary lamellae. The lamellae provide a wide surface, which supports 2-3 Layers of blood capillaries. Pigmentation is highest at the distal ends of the secondary and tertiary Lamella where blood capillaries are concentrated and very scanty on the primary and the proximal ends of the secondary lamella where the presence of capillaries is much reduced. In contrast to the capillaries of the pleated pecten, the endothelium of the capillaries in the pecten of the ostrich exhibits very few microvilli. These observations suggest that the morphology of the pecten of the ostrich, a flightless ratite bird is unique to the pleated pecten and is designed to meet the balance between optimal vision and large surface area for blood supply and yet ensuring it is kept firmly erect within the vitreous.

Ultrastructural features of the follicular wall in developing follicles of the sexually immature ostrich (Struthio camelus)

The ultrastructure of the follicular wall in primordial, previtellogenic and vitellogenic follicles of the sexually immature ostrich is described in the present study. The follicular wall consists of a zona radiata, granulosa cell layer, basal lamina and thecal layer. Cytoplasmic processes from the plasma membranes of the granulosa cell layer and the ovocyte form the zona radiata in previtellogenic and vitellogenic follicles. The granulosa cell layer transforms from simple cuboidal epithelium in primordial follicles to simple columnar or pseudostratified columnar epithelium in previtellogenic and vitellogenic follicles. Transosomes were observed along the apical and lateral plasma membranes of granulosa cells. The thecal layer in previtellogenic and vitellogenic follicles consists of interna and externa components. The fibroblasts in the theca externa contain microfilaments, which are thought to be actin filaments. The study revealed ultrastructural features, which are associated with the transportation of yolk precursors and nutrients into the ovoplasm. In addition, the study indicates that, although the cells in the theca externa contain microfilaments, they do not possess the ultrastructural characteristics of smooth muscle cells.

A Morphological and Immunohistochemical Study of Healthy and Atretic Follicles in the Ovary of the Sexually Immature Ostrich (Struthio camelus)

The morphology of healthy and atretic follicles in the ovary of the sexually immature ostrich was described in the present study. In addition, the distribution of the intermediate filaments desmin, vimentin and smooth muscle actin, in these ovarian follicles, was demonstrated. Healthy and atretic primordial, pre-vitellogenic and vitellogenic follicles were present in the ovaries of the sexually immature ostrich. Atresia occurred during all stages of follicular development. Atretic primordial and pre-vitellogenic follicles were characterized by the presence of a shrunken oocyte surrounded by a multilayered granulosa cell layer. Two forms of atresia (types 1 and 2) were identified in vitellogenic follicles. In the advanced stages of type 1 atresia the follicle was dominated by a hyalinized mass. In contrast, in type 2 atresia the granulosa and theca interna cells differentiated into interstitial gland cells. Positive immunostaining for desmin was observed in the granulosa cells of only healthy primordial and pre-vitellogenic follicles. Atretic primordial and pre-vitellogenic follicles were immunonegative for desmin. Vimentin immunoreactivity was demonstrated in the granulosa cells of all follicles except the vitellogenic atretic follicles. The results of the present study indicate that ovarian follicles in the sexually immature ostrich undergo a cycle of growth and regression, which is similar to that reported in other avian species. Furthermore, based on the results of the immunohistochemical study, it would appear that the distribution and immunostaining of intermediate filaments changes during follicular development and atresia.

The morphology of the efferent ducts of the testis of the ostrich, a primitive bird

The efferent duct of the ostrich consists of two segments, the proximal efferent duct (PED) and the distal efferent duct (DED) that are continuous, as in some other birds. Both segments of the duct possess an epithelium comprising non-ciliated and ciliated cells in varying proportions between the two segments. The non-ciliated cell (type I) of the PED contains a well-developed, subapical endocytic apparatus of apical tubules and endocytic vacuoles, a solitary, large, heterogeneous lipid droplet, and numerous, oval, dense bodies in the supranuclear region of the cell. Mitochondria tend to concentrate in the basal part of the cell. Intercellular spaces between the non-ciliated cells are enlarged, especially in the basal half of the epithelium. Together, these morphological features confer on the PED an efficient fluid absorption capability. The DED epithelium displays the type II non-ciliated cell whose poorly developed subapical endocytic apparatus as well as the absence of dilated basal intercellular spaces indicate its limited fluid absorptive capacity.

Morphological and histological study of the ostrich (Struthio Camelus L.) liver and biliary system

The peculiarity of the digestive system of the ostrich (Struthio Camelus L.), which is characterized by the continuous production of bile, led us to undertake macroscopical and histological studies of the liver and its biliary system, since very little bibliographic data exist on the subject. For this purpose we observed the organs of male and female ostriches 16-18 months of age, in situ, in order to describe their location, relationships and morphology. Samples of the liver were processed for observation by light microscopy; samples of the hepatoenteric duct were processed for observation by light and electron microscopy. Our findings regarding the liver revealed the presence of two lobes: a left lobe, subdivided into three lobes, and a right undivided lobe. There was no gall-bladder. The histological picture showed unlimited hepatic lobules, with hepatocytes arranged in cord-like fashion two cells thick. A large hepatoenteric duct arose from the porta hepatis, and opened into a papilla in the descending limb of the duodenum. The mucosa of the duct was lined by simple columnar epithelium consisting of cells having the same morphological cytoplasmatic features but distinguished by either a light or a dark nucleus.

Sensitive innervation of the copulatory organ in Struthio camelus: comparison to the corresponding district in female proctodeum

The AA. have studied the nerve component of male copulatory organ and ventral part of female proctodeum in the ostrich. This paper represents the concluding part of the plan of research that aimed to verify some data and hypothesis referred in previous observations. The innervation of the considered districts was always constituted by autonomic and sensitive somatic nerve components. The autonomic innervation was represented by isolated and grouped ganglion cells located along the course of nerve bundles or in the point where different nerve bundles converged. This nerve component was frequently in close connection with the blood vessels. The sensitive somatic innervation was constituted by free and capsulated nerve endings. The latter, always supplied by a typical structure and morphologically classified as Pacini, Pacini-like and genital's corpuscles, could be found either isolated or grouped within the different layers of both the examined anatomical territories. The grouped corpuscles, in particular Pacini's corpuscles, could organize simple and complex flower sprays, opposito-polar corpuscles and poikilomorphous fibres. For the first time the capsule's lamellar organization in Pacini's corpuscles in Birds was documented by means of light microscope. The occurrence of genital corpuscles seemed to be exclusive in the ventral part of female ostrich proctodeum, corresponding to the male site in which lies the copulatory organ.

Morphological Features of the Luminal Surface of the Magnum in the Sexually Immature Ostrich (Struthio camelus)

Summary Observations were made, using scanning electron microscopy, of the surface features of the magnum in the immature ostrich during periods of ovarian inactivity, activity and regression. In birds with inactive ovaries the luminal surface of the magnum was lined with non-ciliated cells, which were densely covered by microvilli. In contrast, the magnum in birds with active ovaries was composed of ciliated and non-ciliated cells. The distribution of ciliated cells was not uniform, with clumps of cilia occurring next to non-ciliated areas. Samples collected from birds with regressing ovaries, during periods of decreasing daylength, revealed that the magnum was undergoing involution. The deciliation of ciliated cells and the presence of short microvilli on non-ciliated cells characterized magnal regression. These results suggest that ovarian activity and changes in daylength have a profound effect on the surface features of the magnum in the immature ostrich.

Gender-Specific Reproductive Tissue in Ratites and Tyrannosaurus rex

Unambiguous indicators of gender in dinosaurs are usually lost during fossilization, along with other aspects of soft tissue anatomy. We report the presence of endosteally derived bone tissues lining the interior marrow cavities of portions of Tyrannosaurus rex (Museum of the Rockies specimen number 1125) hindlimb elements, and we hypothesize that these tissues are homologous to specialized avian tissues known as medullary bone. Because medullary bone is unique to female birds, its discovery in extinct dinosaurs solidifies the link between dinosaurs and birds, suggests similar reproductive strategies, and provides an objective means of gender differentiation in dinosaurs.

Histochemical and morphometrical characterization and distribution of fibre types in four muscles of ostrich (Struthio camelus)

A staining procedure used for simultaneously determining three different fibre types in single sections bovine, porcine or ovine skeletal muscle was modified for use with ostrich skeletal muscle. The muscle fibres of gastrocnemius pars externa, tibialis cranialis caput tibiale, tibialis cranialis caput femorale and fibularis longus tendo caudalis were studied. The histochemical results revealed the presence of three types of fibre only in the gastrocnemius pars externa muscle: fast-twitch glycolytic fibres (FG), fast-twitch oxidative glycolytic fibres (FOG) and slow-twitch oxidative fibres (SO), while in the other muscles the FG fibres were absent. The percentage distribution of fibres types showed a higher incidence of SO fibres compared to FOG fibres in tibialis cranialis caput femorale and tibialis cranialis caput tibiale muscles, while it was opposite in the case of the fibularis longus tendo caudalis muscle. In the gastrocnemius pars externa muscle the FG fibres outnumber the other fibres, followed by the SO and FOG fibres. The results of the analysis of variance show significant interaction between muscle x fibre type for every morphometric parameter evaluated. Differences about value of fibres area exists between tibialis cranialis caput femorale and fibularis longus tendo caudalis muscles. Both fibre types in tibialis cranialis caput tibiale muscle have mean values of transversal section area smaller than tibialis cranialis caput femorale. The other morphometric parameters show a similar trend. The gastrocnemius pars externa muscle presents similar dimensions of muscle fibres for the FG and FOG types, and significantly smaller for the SO type.

Autonomic and sensitive somatic innervation of the ostrich elbow and knee joints articular capsule

The present research was carried out on the fibrous layer of the ostrich's elbow and knee joints articular capsule, employing opportunely modified gold chloride Ruffini's method, to study the autonomic and sensitive somatic nerve components. The distribution of both nerve components followed frequently the vascular networks. The autonomic innervation was represented by isolated or grouped ganglion cells, frequently placed along the course of nerve trunks, close to the epineurium or located within the perineural connective tissue. The sensitive somatic innervation was constituted by free and encapsulated corpuscles. The last one, morphologically classified as Pacini, Pacini-like and Golgi-Mazzoni's corpuscles, were found isolated or grouped to constitute simple and complex flower sprays, "opposito-polar corpuscles" and "poichilomorphous fibres". The very few Golgi-Mazzoni's corpuscles were found only in the knee joint articular capsule. The two nerve components, found in the considered districts, did not shown significant quanti-qualitative and topographic differences. This datum, at least in appearance, seems to conflict with the ostrich functional aptitudes. In fact, the ostrich is a bird unable to fly but very able to run.

Extracellular matrix of ostrich articular cartilage

The composition and organization of the extracellular matrix of ostrich articular cartilage was investigated, using samples from the proximal and distal surfaces of the tarsometatarsus. For morphological analysis, sections were stained with toluidine blue and analyzed by polarized light microscopy. For biochemical analysis, extracellular matrix components were extracted with 4 M guanidinium chloride, fractionated on DEAE-Sephacel and analyzed by SDS-PAGE. Glycosaminoglycans were analyzed by electrophoresis in agarose gels. Structural analysis showed that the fibrils were arranged in different directions, especially on the distal surface. The protein and glycosaminoglycan contents of this region were higher than in the other regions. SDS-PAGE showed the presence of proteins with molecular masses ranging from 17 to 121 kDa and polydisperse components of 67, 80-100, and 250-300 kDa in all regions. The analysis of glycosaminoglycans in agarose-propylene diamine gels revealed the presence of only chondroitin-sulfate. The electrophoretic band corresponding to putative decorin was a small proteoglycan containing chondroitin-sufate and not dermatan-sulfate, unlike other cartilages. The higher amounts of proteins and glycosaminoglycans and the multidirectional arrangement of fibrils seen in the distal region may be correlated with the higher compression normally exerted on this region.

The sensitive innervation of the ostrich nasal mucosa

The sensitive innervation of the ostrich's nasal mucosa, through impregnative gold chloride methods, was investigated. The autonomy innervation, constituted by ganglion cells placed along the course of nerve trunks was particularly represented in the respiratory tract of the nasal cavity. The somatic nerve component, composed by free and capsulated endings, was especially distributed in the vestibular district. The nerve corpuscles were morphologically classified as Pacini, Pacini-like, Golgi-Mazzoni and Herbst. Further investigations must be expected to attribute an effective functional role particularly to this last nerve component.

Anatomical description of the muscles of the pelvic limb in the ostrich (Struthio camelus)

Dissections of 12 formalin-fixed ostriches were performed to give anatomical descriptions of the muscles and tendons of the pelvic, femoral, tibiotarsal, tarsometatarsal and digital regions. In the pelvic limb of the ostrich, 36 muscles can be determined. The ostrich lacks those muscles to the first and second toes (with exception of the M. flexor hallucis longus), which can be found in birds with four toes. The Mm. iliotrochantericus medius, plantaris, extensor proprius digiti IV and adductor digiti IV, which are present in other birds, are also absent, whereas the Mm. pectineus and femorotibialis accessorius additionally occur in the ostrich. The Pars supramedialis is a tendineous part of the M. gastrocnemius, on which the Mm. flexor cruris lateralis and flexor cruris medialis insert by means of a fascial sheet. The caudal part of the M. iliofibularis terminates within the caudal aspect of the superficial fascia cruris. The caudal heads of the Mm. flexor perforatus digiti III and flexor perforatus digiti IV as well as the M. flexor hallucis longus have a common origin on the Fossa poplitea of the femur. The lateral head of the M. flexor perforatus digiti IV and the femoral head of the M. flexor perforans et perforatus digiti III originate on the tendon of origin of the Caput laterale of the M. flexor perforatus digiti III. Furthermore, the last named tendon fuses with the tendon of insertion of the M. ambiens. The M. extensor proprius digiti III originates on a plate-like fascial sheet part of the dorsal joint capsule of the intertarsal joint.

The Fine Structure of the Harderian Gland in the Ostrich (Struthio camelus)

The Harderian gland of the ostrich (Struthio camelus) is a tubuloalveolar gland containing holocrine secreting epithelial cells. The gland epithelium is composed of two different cell types, which can be classified as type I and type II. These cells contain dense secretory vesicles in their cytoplasm and they are connected laterally with desmosomes. At the basal site of these cells, myoepithelial cells are present. Plasma cells are observed in the subepithelial region of the gland. In the interlobular trabeculae, forming the gland stroma, fibroblasts, blood vessels and nerve fibres are included. Another important finding in the ostrich Harderian gland is the presence of homogeneous material.

Resistance to tearing of calf and ostrich pericardium: Influence of the type of suture material and the direction of the suture line

The tearing of the valve leaflet of a cardiac bioprosthesis can cause early failure of this device, which is employed to replace a diseased native valve. This report involves the study of the behavior of 312 tissue samples (152 of calf pericardium and 160 of ostrich pericardium) treated with glutaraldehyde and subsequently subjected to tear testing. The samples were cut in the two principal directions: longitudinally, or root to apex, and transversely. They included a series of control samples that were left unsutured, and the remaining samples were repaired with the use of two different suture techniques: a running suture in the direction of the load and a telescoping suture perpendicular to the load. Four commercially available suture materials were employed: Pronova, nylon, Gore-Tex, or silk. The unsutured control samples of both types of pericardium exhibited a similar anisotropic behavior in the tear test. The mean resistance to tearing of the calf pericardium was 24.29 kN m in samples cut longitudinally and 34.78 kN m in those cut transversely (p =.03); the values were 28.08 kN m and 37.12 kN m (p =.002), respectively, in ostrich pericardium. The series repaired with the telescoping suture always exhibited greater resistance to tearing, with values that ranged between 44.34 and 64.27 kN for the samples of calf pericardium and from 41.65 to 47.65 kN for those obtained from ostrich. These assays confirm the anisotropic behavior of calf and ostrich pericardium treated with glutaraldehyde when subjected to tear testing, as well as the loss of this behavior in ostrich pericardium after suturing. Suturing techniques, such as the telescoping model, that provide a greater resistance to tearing should be studied for use in the design of the valve leaflets of cardiac bioprostheses made of biological materials.

Fine Structure of the Retinal Pigment Epithelium, Bruch's Membrane and Choriocapillaris in the Ostrich (Struthio camelus)

The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris in the ostrich (Struthio camelus) was investigated by using light microscopy and transmission electron microscopy. In this species, the RPE consisted of a single layer of low columnar cells. The epithelial cells were joined laterally by two type junctions, zonulae occludentes and zonulae adherentes located in the midregion of the cells. These cells displayed numerous deep basal infoldings and thick extensive apical processes, which enclosed the outer segments of the rods. The epithelial cell nuclei were large, vesicular and located basally within the epithelial cells. Smooth endoplasmic reticulum was very abundant, while rough endoplasmic reticulum was scarce. Mitochondria of various shapes were abundant basally while polysomes were plentiful and widespread. In the light-adapted state melanosomes were located in the apical region and in apical processes of the epithelial cells. Myeloid bodies were large, numerous and often showed ribosomes on their outer surface. Bruch's membrane (complexus basalis) was typical pentalaminate throughout the retina, as noted in the majority of other vertebrates. The endothelium of the choriocapillaris facing Bruch's membrane was extremely thin but only moderately fenestrated. Some of the fenestrations displayed a double-layered diaphragm while the majority showed the more typical single-layered diaphragm noted in most species.

Homologies of thetransversospinalis muscles in the anterior presacral region of Sauria (crown Diapsida)

Homologies of muscles of the m. transversospinalis group in the dorsal and cervical regions in Sauria are established based on detailed dissections and published accounts of lepidosaurs, crocodylians, and birds. Attachments and directions of tendons comprising this muscle group are fairly conserved among the saurian clades, enabling rather robust inferences on muscle homologies. The innervation pattern indicates that mm. ascendentes are the most lateral muscles of the m. transversospinalis group in Aves, and are inferred to be homologous with the crocodylian m. tendinoarticularis based on their topological similarities. It is suggested here that the lepidosaurian articulo-parietalis part of m. longissimus cervico-capitis actually belongs to the m. transversospinalis group because its tendons of origin are shared with those of m. semispinalis. The avian m. complexus and the lateral part of the crocodylian m. transversospinalis capitis have origins and insertions similar to this lepidosaurian muscle, and are proposed to be homologous with the latter. In some birds, m. longus colli dorsalis, pars profunda continues directly into the anterior cervical region as m. splenius accessorius, suggesting a serially homologous relationship. Similarly, m. splenius anticus continues anteriorly from m. longus colli dorsalis, pars cranialis, and both of these muscles lie dorsal to m. splenius accessorius. Therefore, the currently used nomenclature that regards m. splenius accessorius as a part of m. longus colli dorsalis, pars cranialis and that regards m. splenius anticus as a part of the former muscle does not accurately reflect the serial homologies among these muscles and may not be justified.

The morphological features of the rete testis of the ostrich ( Struthio camelus )

The epithelium of the rete testis of the ostrich is simple cuboidal to columnar in nature, unlike the more flattened epithelium encountered in other non-passerine birds. A solitary cilium projects into the ductal lumen. A unique lateral cell membrane modification, similar, in some respects, to a hemi-desmosome, occurs frequently along the length of this membrane. The lateral cell membrane is complexly folded, and the cell contains an abundance of intermediate filaments, particularly in the vicinity of the nucleus and the internal surface of the basal cell membrane. The Golgi complex and endoplasmic reticulum are moderately developed. Another unique feature of the cell is the presence of a solitary, large, heterogeneous lipid body/droplet situated in the immediate supranuclear region of the cell. Overall, the cell structure conveys the impression of a metabolically active cell, which has the capability of transporting material from the duct lumen to the basal part of the cell, and of protein synthesis, apparently much in excess of what is necessary for cellular maintenance and sustenance.

Ultrasonography of the female reproductive organs in farmed ostriches (Struthio camelus spp.)

The main objective of this study was to determine whether transcutaneous ultrasonography could be used as a diagnostic tool to monitor the reproductive organs of female breeding ostriches. An additional aim was to investigate whether the use of this technique could facilitate prediction of the start or end of the egg production season. A technique for on-farm ultrasound scanning is described and examples of ultrasonographic images of different ovarian structures, developing ova and eggs within the genital tract are presented. These data were obtained by scanning mature female breeding ostriches (n=8). In vivo scanning took place a day prior to slaughter, and immediately after slaughter the reproductive organs were scanned in vitro in a water bath. By comparing ultrasonographic images with post mortem ovarian morphology, it appeared that the following morphological structures can be identified using ultrasonography: ovarian follicles of different sizes (diameter (phi) 1-9 cm), atretic follicles, post-ovulatory follicles (POFs), ova at different stages of development and eggs within the genital tract. Of the number of follicles counted during post mortem investigation, 58% (95% confidence interval 0.41-0.79) had been detected during previous in vivo examination. In the second part of our study, ultrasonographic scans were made at weekly intervals in two farmed female ostriches (n=2) during the breeding season in order to determine the predictive value of the technique. By comparing the images of ovarian activity with individual egg production of these hens, preliminary evidence was obtained that scanning might be of value in predicting egg production, especially at the start and the end of the breeding season. It is concluded that transcutaneous ultrasound scanning in mature female breeding ostriches is an easy, noninvasive technique for the monitoring of ovarian (in)activity, for visualization of different functional ovarian structures, for following the development of individual ova and for visualization of an egg with calciferous shell within the oviduct, and that this technique will be a valuable tool in future research on reproductive physiology and pathology, and the development of more advanced reproductive technologies, such as artificial insemination.

RADIOGRAPHIC GASTROINTESTINAL CONTRAST STUDY IN THE OSTRICH (STRUTHIO CAMELUS)

Ten gastrointestinal contrast studies were performed with barium on seven clinically healthy ostriches. Concentrations of 25-100% w/vol liquid barium sulfate at 7 and 10 ml/kg were administered by stomach tube after withholding food for 16 h. A 6-frame technique for left-to-right lateral views in standing and a 3-frame technique for the dorsoventral views in sternally recumbent adult ostriches were used for survey and contrast radiographs. Objectives were to describe the appearance of the normal gastrointestinal tract with contrast radiography and to provide a guideline for optimal dosage and concentration of barium sulfate as well as a reliable protocol for frequency of radiographs. Structures that were consistently identified included the esophagus, proventriculus, ventriculus, duodenum, jejunum, proximal, and distal rectum. Due to the superimposition of the remainder of the small intestine, individual components were difficult to differentiate. The caeca were inconsistently highlighted and only for a short time. The ventral pouch of the coprodeum never filled with contrast medium.

A study on the morphological structure of syrinx in ostriches (Struthio camelus)

The aim of this study was to investigate the topographical, anatomical and histological characteristics of syrinx in five ostriches. It was observed that the syrinx in the ostrich was tracheobronchial type and was composed of three different cartilage groups, namely tympanum, cartilagines (cartt.) tracheosyringeales and cartt. bronchosyringeales. Tympanum and cartt. tracheosyringeales were formed from three and four cartilage rings, respectively, while cartt. bronchosyringeales was formed from three C-shaped cartilage rings. The pessulus did not contain any ossified or cartilaginous tissues and was made up of a double folded mucous membrane extending dorsoventrally from median walls of bronchus primarius into the cavum syringis.

On the sensitive innervation of the ostrich's foot pads

The sensitive and autonomic innervation of foot pads in the ostrich was studied employing an usual histological technique as hematoxylin-eosin or different gold chloride impregnations. The autonomic innervation is represented by isolated or grouped ganglion cells located along the course of nerve bundles. The sensitive somatic innervation is composed by free and capsulated nerve endings usually distributed in the thickness of the connective arrangement of the foot pads, in the most superficial part the first one, while the latter was generally located close to the blood vessels. The capsulated nerve endings, morphologically classified as Pacini, Pacini-like and Herbst corpuscles, show the typical structure. They are not uniformly distributed throughout the considered districts and their number are always higher in the plantar pad compared with digital pads. These corpuscles could be found isolated or assembled to organize simple flower-sprays and to constitute opposito-polar corpuscles. The Authors have put forward a hypothesis on the possible functional role of the above-mentioned nerve components.

Progesterone and oestrogen receptor immunoreactivity in the vagina of the immature ostrich, Struthio camelus

1. The presence of sperm storage tubules in the cranial, middle and caudal regions of the vagina in the immature ostrich was studied. In addition, progesterone and oestrogen receptor immunoreactivity in these regions was investigated. 2. Sperm storage tubules were observed only in birds with active ovaries. Progesterone receptor immunoreactivity was more intense in birds with active ovaries, whilst immunostaining for the oestrogen receptor was absent in birds with both active and inactive ovaries. 3. These results suggest that steroid hormones produced by the active ovary mediate the activation of the progesterone receptor.

The purification and characterisation of m-calpain from ostrich brain

Calpains are intracellular cysteine proteases activated in a Ca(2+)-dependent manner. The purpose of the present study was to investigate the physico-chemical and kinetic properties of ostrich brain m-calpain. m-Calpain was purified by successive chromatographic steps on Toyopearl-Super Q 650s and Pharmacia Mono Q HR 5/5 columns. A Ca(2+) concentration of 5mM and a casein concentration of 5mg/ml were found to be necessary for optimum calpain activity. Ostrich m-calpain exhibited a M(r) of 84K using SDS-PAGE and a M(min) of 79.3K from amino acid analysis. The pH and temperature optima were found to be 7.5 and 37 degrees C, respectively. The amino acid composition of m-calpain revealed 700 residues. The N-terminal sequence of m-calpain showed sequence identity with chicken (27%), human (23%) and rabbit (18%) and Schistoma mansoni (9%).

Radiographic anatomy of the thoraco-abdominal cavity of the ostrich (Struthio camelus)

This study provides a reference for the radiographic anatomy of the thoraco-abdominal cavity of female ostriches as a representative of ratites. One ostrich cadaver, 2 adult and 2 growing ostriches were used. Right lateral radiographs produced by a 6-frame technique and 2 dorsoventral radiographs produced by an adapted 3-frame technique were selected and schematic illustrations of these were labelled to illustrate normal radiographic anatomy. Differences from other avian species and unique features of the ostrich are briefly discussed.

Transcutaneous ultrasonography of the coelomic viscera of the ostrich (Struthio camelus)

Ultrasonographic examinations were performed on clinically healthy growing and adult nonbreeding female ostriches. Multiple acoustic windows and the normal ultrasonographic appearance of the coelomic viscera were described. Good images of the heart and its major vessels, proventriculus, ventriculus, intestines, liver, and kidneys could be obtained. Additionally, an anechoic structure, believed to function as an urinary bladder, could be imaged in the cloacal region. The pancreas, spleen, thyroid glands, ovary, and adrenals could not be seen in this study. General limitations were the size of the ostriches, massive leg and dorsal muscles, large sternum, the extensive air sac system, compact convoluted intestines, and varying amounts of gastrointestinal gas. Ostriches do not posses a gall bladder, and thus it could not be used as a landmark or acoustic window. The extensive air sac system and feathers did not limit the use of ultrasonography as much as anticipated. Imaging of air sacs should, however, be considered to detect pathology such as air sacculitis, which may result in consolidation. Veterinary

A qualitative and quantitative study of the lung of an ostrich,Struthio camelus

The ostrich lung, with its lack of interparabronchial septa, the presence of very shallow atria and exceptional morphometric refinement, structurally resembles those of small, energetic flying birds, whereas it also displays features characteristic of the flightless ratites in which the neopulmo is relatively poorly developed and a segmentum accelerans may be generally lacking. The large size of the bronchial system of the ostrich may help explain the unique shifts in the airflow pathways that must occur from resting to panting breathing, explaining its insensitivity to acid–base imbalance of the blood during sustained panting under thermal stress. The mass-specific volume of the lung is 39.1 cm3kg−1 and the volume density of the exchange tissue is remarkably high (78.31%). The blood–gas (tissue) barrier is relatively thick (0.56μm) but the plasma layer is very thin (0.14μm). In this flightless ratite bird, the mass-specific surface area of the tissue barrier (30.1 cm2g−1), the mass-specific anatomical diffusing capacity of the tissue barrier for oxygen (0.0022mlO2s−1Pa−1kg−1), the mass-specific volume of pulmonary capillary blood (6.25 cm3kg−1) and the mass-specific total anatomical diffusing capacity for oxygen (0.00073mlO2s−1Pa−1kg−1) are equivalent to or exceed those of much smaller highly aerobic volant birds. The distinctive morphological and morphometric features that seem to occur in the ostrich lung may explain how it achieves and maintains high aerobic capacities and endures long thermal panting without experiencing respiratory alkalosis.

Three-dimensional kinematics of skeletal elements in avian prokinetic and rhynchokinetic skulls determined by Roentgen stereophotogrammetry

Several different types of cranial kinesis are present within modern birds, enabling them to move (part of) the upper bill relative to the braincase. This movement of the upper bill results from movement of the quadrate and the pterygoid-palatine complex (PPC). The taxon Palaeognathae is characterised by a very distinct PPC and a special type of cranial kinesis (central kinesis) that is very different from that found in the Neognathae. This has led some authors to hypothesise that there is a functional relationship between the morphology of the PPC and the type of cranial kinesis. This hypothesis is tested here by analysing the movement pattern of both the upper bill and the PPC in birds with three different types of cranial kinesis: prokinesis, distal rhynchokinesis and central rhynchokinesis. Movement patterns were determined using a Roentgen stereophotogrammetry method, which made it possible to detect very small displacements (0.5 mm) of bony elements in three dimensions, while the jaw muscles and ligaments remained intact. We found that in all types of kinesis investigated the movements of the quadrate, jugal bars and PPC are similar. Movement of the quadrate is transferred to the upper beak by the jugal bar and the PPC, which moves almost exclusively forwards and backwards, thereby elevating or depressing the upper bill. The differences between the types of kinesis lie only in the position of the point of rotation. These findings indicate that there is no correlation between the specific morphology of the PPC and the type of cranial kinesis. Several other factors, including the external forces applied during food acquisition, may influence the morphology of the PPC. Differences in PPC morphology therefore appear to be the result of different functional demands acting on the system simultaneously but with different strengths, depending on the species.

Radiography of the thoraco-abdominal cavity of the ostrich (Struthio camelus)

A standard radiographic procedure was developed for the thoraco-abdominal cavity of female nonbreeding ostriches. Positioning, collimation, centering and a technique chart were defined to give reproducible and consistently good quality radiographs. Radiographs were obtained from one adult ostrich cadaver, two adult female ostriches as well as two growing ostriches at various stages. A 6-frame technique was established for lateral views taking the topographic tissue distribution into consideration and using easily palpable landmarks as centering points. Standing true right lateral radiographs are recommended for standard procedures. For dorsoventral exposures a 3-frame technique in the recumbent ostrich was found to be optimal. Birds should be fasted if possible. A technique chart for lateral exposures is provided.

Retinal photoreceptors of paleognathous birds: the ostrich (Struthio camelus) and rhea (Rhea americana)

Microspectrophotometry was used to determine the absorbance spectra of both rod and cone visual pigments and oil droplets from the retinae of the ostrich (Struthio camelus) and rhea (Rhea americana). Light and fluorescence microscopy of whole fresh tissue mounts were used to determine the relative numbers and distribution of oil droplets in the retinae. Both species possessed rods, double cones and four classes of single cone identified by their oil droplets. The rods had lambda max at about 505 nm, whereas three cone pigments were recorded with lambda max at 570, 505 and 445 nm. The P570 pigment was located in both members of the double cones and in a class of single cone containing an R-type oil droplet (lambda cut at 555 nm). The P505 and P445 cone pigments were found in populations of single cones containing Y-type and C-type oil droplets (lambda cut of 500 and 420 nm, respectively). The fourth class of single cone contained a T-type droplet and in the ostrich contained a visual pigment with lambda max at about 405 nm. Double cones possessed a P-type droplet in the principal member and an A-type droplet in the accessory member. The complement of visual pigments and oil droplets, and the ratio of cone types in the ostrich and rhea, are remarkably similar to those found in many groups of neognathous birds.

The surface features of the epithelial lining of the ducts of the epididymis of the ostrich (Struthio camelus)

The luminal appearance of the various ducts of the epididymis of the ostrich was studied by scanning electron microscopy in tissues fixed by immersion in glutaraldehyde. The ductal types were similar to those previously described for some other species of birds. Numerous short microvilli, as well as a single cilium, projected from the apical surface of the rete testis cell. The ciliated cells of the efferent ductules projected tufts of cilia into the ductal lumen, while the non-ciliated cells bore short microvilli. The connecting and epididymal ducts were lined by a columnar cell type whose apical surface bore uniformly distributed microvilli and a single, centrally situated cilium. The spermatozoa found in all ducts of the epididymis bore a distal cytoplasmic droplet. This observation has implications for the maturational process in the ostrich spermatozoon in the epididymis. The surface features of the ducts, except for a few noteworthy differences, were generally similar to those previously described for the male domestic fowl, turkey and duck.