Steps of spermiogenesis in the ostrich (Struthio camelus).

Few studies describe the sequence of morphological events that characterize spermiogenesis in birds. In this paper, the clearly observable steps of spermiogenesis are described and illustrated for the first time in a commercially important ratite, the ostrich, based on light microscopy of toluidine blue-stained plastic sections. Findings were supplemented and supported by ultrastructural observations, PNA labeling of acrosome development, and immunocytochemical labeling of isolated spermatogenic cells. Spermiogenesis in the ostrich followed the general pattern described in non-passerine birds. Eight steps were identified based on changes in nuclear shape and contents, positioning of the centriolar complex, and acrosome development. Only two steps could be recognized with certainty during development of the round spermatid which contributed to the fewer steps recorded for the ostrich compared to that described in some other bird species. The only lectin that displayed acrosome reactivity was PNA and only for the first three steps of spermiogenesis. This suggests that organizational and/or compositional changes may occur in the acrosome during development and merits further investigation. Immunological labeling provided additional evidence to support the finding of previous studies that the tip of the nucleus in the ostrich is shaped by the forming acrosome and not by the microtubular manchette. To our knowledge, this is the first complete description of spermiogenesis in ostrich and one of few in any avian species. In addition to comparative reproduction and animal science, this work has implications for evolutionary biology as the reported germ cell features provide a bridge between reptile and ratite-avian spermatogenesis.

Ostrich ejaculate characteristics and male libido around equinox and solstice dates.

The study evaluated the effect of time of the year in which changes in photoperiod occurs on ostrich semen characteristics and male libido. Semen was collected for 5 days before, on and 5 days after winter solstice (21 June 2016), spring equinox (22 September 2016), summer solstice (21 December 2016) and autumn equinox (20 March 2017) in the southern hemisphere. Semen was collected from 10 South African Black ostrich males (average age ± standard deviation; 4.5 ± 2.27 years) using the dummy female. Semen volume, sperm concentration, total sperm per ejaculate, sperm motility traits, percentage of normal sperm, head and tail abnormalities and percentage of affected sperm in the hypo-osmotic swelling test (HOS) were evaluated. Male libido defined as the willingness of males to mount the dummy female was also recorded. Semen samples collected around summer solstice, spring and autumn equinox were higher in sperm concentration and sperm output compared with winter solstice (P < 0.05). Study periods did not influence semen volume, sperm motility traits, the percentage of normal sperm, head abnormalities and HOS. Tail abnormalities were higher around winter solstice than around spring equinox (P < 0.05). Male libido and the success of semen collection were significantly higher around spring equinox (P < 0.05). Changes in photoperiod in the southern hemisphere do not affect semen production in ostriches. However, high sperm output and male libido around spring equinox and summer solstice dates suggest that these periods may be preferred for semen collection for artificial insemination and storage purposes.

Sperm macrocephaly syndrome in the ostrich Struthio camelus: morphological characteristics and implications for motility.

Sperm macrocephaly syndrome (SMS) is characterised by a high percentage of spermatozoa with enlarged heads and multiple tails, and is related to infertility. Although this multiple sperm defect has been described in other mammalian species, little is known about this anomaly in birds. Morphological examination of semen from nine South African black ostriches (Struthio camelus var. domesticus) involved in an AI trial revealed the variable presence of spermatozoa with large heads and multiple tails. Ultrastructural features of the defect were similar to those reported in mammals except that the multiple tails were collectively bound within the plasmalemma. The tails were of similar length and structure to those of normal spermatozoa, and the heads were 1.6-fold longer, emphasising the uniformity of the anomaly across vertebrate species. Flow cytometry identified these cells as diploid and computer-aided sperm analysis revealed that they swim slower but straighter than normal spermatozoa, probably due to the increased drag of the large head and constrained movement of the merged multiple tails. The high incidence of this defect in one male ostrich indicates that, although rare, SMS can occur in birds and may potentially have an adverse effect on breeding programs, particularly for endangered species.

Development of the germinal ridge and ovary in the African elephant (Loxodonta africana).

The follicular reserve and its ontogeny in the elephant are of interest because elephants have the longest reproductive life of all land-based mammals. They also have the longest recorded pregnancy, which allows a protracted view of the series of significant events involved in the development of the embryonic and fetal gonads. The large elephant population of Zimbabwe provided the opportunity to collect conceptuses from elephants culled for management reasons and hunted professionally. Five embryos aged 76-96 days and the ovaries of four fetuses aged 4.8-11.2 months were fixed in 4% buffered formalin and studied by conventional histological sectioning and a stereological protocol to calculate the follicle reserve of each fetus. These observations enabled the conclusion that the migration of primordial germ cells into the indifferent gonad terminates at around 76 days of gestation while entry of oogonia into meiosis along with first follicle formation starts at around 5 months. Peak numbers of follicles are present by mid-gestation towards the end of the 6-month mitotic-meiotic transition period. It appears that the cortex of the elephant fetal ovary at mid-gestation (11 months) has already reached a developmental stage exhibited by the ovaries of many other mammals at full term.

The composition of egg yolk absorbed by fasted ostrich (Struthio camelus L.) chicks from 1 to 7 days posthatching and for ostrich (Struthio camelus L.) chicks from 1 to 16 days posthatching on a prestarter broiler diet.

This study was performed to obtain information on yolk utilization in fasted and fed ostrich chicks posthatching. The fasted trial lasted for 7 d, whereas the fed trial continued for 16 d. Fasted ostrich chicks showed a decrease of 31.3 g of BW, with yolk weight decreasing by 28.9 g daily after hatching. Yolk weight comprised 28% of 1-d-old ostrich chick BW and decreased to 12% at 7 d of age. Only 44.4% of the fasted ostrich chick yolk was assimilated over the trial period. Crude protein content of the yolk decreased by 13.2 g daily. Fat content increased by 1.77% daily, whereas total yolk fat weight decreased with 8.91 g daily. Slaughter weight of fed ostrich chicks increased, with yolk weight decreasing by 16.3 g daily. Yolk content for fed ostrich chicks was 26% of BW at 2 d of age. Ostrich chicks absorb 30% of yolk over the first 4 d, 67% after 8 d, and only deplete the yolk after 14 d posthatch. Fasted ostrich chicks absorbed the yolk content at a rate of 28.9 g/d, compared with 22.3 g/d over the first 8 d and 16.3 g/d over the 16 d for fed ostrich chicks. The CP content of the yolk decreased by 6.84 g daily in fed ostrich chicks, whereas fat content of the yolk increased by 1.39% daily, although total yolk fat weight decreased by 6.61 g daily. Yolk weight and total CP decreased faster over the first 7 d in the fasted ostrich chicks compared with the fed ostrich chicks, which indicated that the decrease in yolk weight could be attributed to absorption of protein from the yolk. Fat content decreased faster over the first 8 d from the yolk of the fed ostrich chicks compared with that from the yolk of the fasted ostrich chicks, which could indicate that external feed has a positive influence on the absorption of fat from the yolk content.

Morphology of the tongue of the emu (Dromaius novaehollandiae). II. Histological features.

Although a number of brief, fragmented descriptions have been provided on the gross morphology of the ratite tongue, very few studies have documented the histological structure of this organ. This paper presents the first definitive histological description of the emu tongue and reviews, consolidates and compares the scattered information on the histology of the ratite tongue available in the literature. Five tongues were removed from heads obtained from birds at slaughter and fixed in 10% neutral buffered formalin. Appropriate longitudinal and transverse segments were removed, routinely processed for light microscopy, and sections examined after staining with H & E and PAS. The entire tongue (body and root) is invested by a non-keratinized stratified squamous epithelium. The supporting connective tissue of the tongue dorsum displays only large, simple branched tubular mucus-secreting glands, whereas the caudal tongue body ventrum and tongue root, in addition to these glands, also exhibits small, simple tubular mucus-secreting glands. Herbst corpuscles are associated with the large, simple branched glands. Lymphoid tissue is restricted to the tongue ventrum and is particularly obvious at the junction of the ventral tongue body and frenulum where a large aggregation of diffuse lymphoid tissue, with nodular tissue proximally, was consistently observed. A structure resembling a taste bud was located in the epithelium on the caudal extremity of the tongue root of one bird. This is the first reported observation of taste buds in ratites. Forming the core of the tongue body is the cartilaginous paraglossum lying dorsal to the partially ossified rostral projection of the basihyale. The histological features of the emu tongue are generally similar to those described for the greater rhea and ostrich, except that taste buds were not identified in these species. The results would suggest that the emu tongue functions as a sensory organ, both for taste and touch (by virtue of taste receptors and Herbst corpuscles, respectively), as well as fulfilling an immunological function.

Morphology of the tongue of the emu (Dromaius novaehollandiae). I. Gross anatomical features and topography.

Despite numerous papers addressing the topic, the gross morphology of the ratite tongue and more specifically that of the emu, has been superficially or poorly described. This paper presents the first definitive macroscopic description of the emu tongue and reviews, consolidates and compares the scattered information on the gross morphology of the ratite tongue available in the literature. Twenty-three heads obtained from birds at slaughter were used for this study. Specimens were fixed in 10 % neutral buffered formalin, rinsed and the gross anatomy described. The emu tongue is divided into a body and a root. The body is triangular, dorsoventrally flattened, pigmented and displays caudally directed lingual papillae on both the lateral and caudal margins. The root, a more conspicuous structure in comparison to other ratites, is triangular, with a raised bulbous component folding over the rostral part of the laryngeal fissure. Following the general trend in ratites, the emu tongue is greatly reduced in comparison to the bill length and is specifically adapted for swallowing during the cranioinertial method of feeding employed by palaeognaths. This study revealed that it is not only the shape of the tongue that differs between ratites, as previously reported, but also its colour, appearance of its margins and root, and its length in comparison to the bill, and the shape of the paraglossum.

Macroscopic features of the venous drainage of the reproductive system of the male ostrich (Struthio camelus).

The macroscopic features of the venous drainage of the reproductive system of the male ostrich were studied in six pre-pubertal and three sexually mature and active birds. Each testis was drained by one to four testicular veins. The right testicular veins drained the right testis and epididymis and its appendix to the caudal vena cava and to the right common iliac vein, whereas the left testicular veins drained the left testis and epididymis and its appendix exclusively to the left common iliac vein. A number of variations in the drainage pattern based on the point of entry and number of testicular veins were observed. The cranial aspect of the testis was also linked to the caudal vena cava or common iliac vein via the adrenal veins. The cranial, middle and caudal segments of the ductus deferens (and ureter) were drained by the cranial, middle and caudal ureterodeferential veins respectively, to the caudal testicular veins, the caudal renal veins and pudendal/caudal part of the internal iliac veins. In some specimens, the caudal ureterodeferential veins also drained into the caudal mesenteric vein. The surface of the phallus was drained by tributaries of the pudendal vein. The basic pattern of venous drainage of the reproductive organs of the male ostrich was generally similar to that described for the domestic fowl. However, important differences, including the partial fusion of the caudal renal veins, drainage of the cranial aspect of the testes via the adrenal veins, drainage of the caudal ureterodeferential veins into the caudal mesenteric vein and the presence of veins draining the surface of the phallus, were observed. Although significant, these differences may simply reflect variations in the normal pattern of venous drainage of the reproductive tract of birds which could be verified by studying more specimens and more species.

Muscles and fascial elements of the antebrachium and manus of the African elephant (Loxodonta africana, Blumenbach 1797): starring comparative and functional considerations.

The structure of the limbs of elephants is unusual among mammals. In African elephants (Loxodonta africana, Blumenbach 1797), the front limbs serve to support the greatest part of the body mass of the largest land animal. In this study, we present new and detailed anatomical data regarding muscular and specific fascial structures of the lower front limb which were examined by means of standard anatomical and histological techniques. The muscles and tendons of the forearm (antebrachium) and hand (manus) are tightly surrounded by thick, highly elastic fascial layers which fuse with the lacertus (lac.) fibrosus and the so-called ligamentum (lig.) humeroulnare. A well-developed musculus (m.) brachioradialis occupies the proximolateral aspect of the forearm and its tendon inserts together with the lac. fibrosus on the os carpi intermedium. The lac. fibrosus, the lig. humeroulnare and the m. flexor carpi radialis reveal a large proportion of elastic fibres. These three structures may play an important role in storing strain energy thus promoting energy-saving locomotion. On the palmar aspect of the carpus, metacarpus and digits, short flexor, abductor, adductor, lumbricales and interossei muscles are present, whereas supinator muscles are absent in all specimens. The short muscles of the hand together with specific dorsal tendons enable precise movements of specific toes.

Histo-morphology of the uterus and early placenta of the African buffalo (Syncerus caffer) and comparative placentome morphology of the African buffalo and cattle (Bos taurus).

Differences exist in reproductive physiology between African buffalo (Syncerus caffer), cattle (Bos taurus) and water buffalo (Bubalus bubalis). The aim of this study was to histo-morphologically compare the anatomy of non-pregnant and pregnant uteri of buffalo and cattle. Two non-pregnant uteri and placentae of six pregnant African buffalo were used. Early placentome formation (fetal crown rump length (CRL): 2-17.5 cm) in S. caffer and B. taurus was compared. The endometrium of buffalo uteri comprises round to ovoid, dome-shaped and gland-free caruncles. A predominantly simple columnar epithelium of non-ciliated cells covers caruncular tissue, while, additionally, ciliated cells occur in the epithelium of the intercaruncular areas and within the simple columnar or pseudostratified epithelium of the endometrial glands. During early gestation, multiple placentomes develop. Unlike the placentomes in cattle at similar CRL, buffalo placentomes do not develop a caruncular stalk. The sessile, dome-shaped buffalo placentome has simple, slightly conical villi branching less than in cattle, thus indicating different and less complex feto-maternal interdigitation than seen in the latter. A synepitheliochorial interhaemal barrier can be expected in the buffalo placenta, as the occurrence and ultrastructure of trophoblast giant cells resemble those described in cattle.

Morphology of the gular valve of the Nile crocodile, Crocodylus niloticus (Laurenti, 1768).

The morphology of the gular valve of the Nile crocodile was studied on the heads of eight 2.5-3-year-old commercially raised Nile crocodiles (Crocodylus niloticus). A description of the macroscopic and microscopic features of the gular valve is presented and the results are compared with published information on this species and other Crocodylia. The histological features are supplemented by information supplied by scanning electron microscopy (SEM). Anatomically, the dorsal and ventral components of the gular valve in the Nile crocodile form an efficient seal that effectively separates the oral and pharyngeal cavities consistent with the natural behavior and feeding habits of this animal. The gular valve is more complex in nature than superficial observations would suggest, with the dorsal and ventral folds being complemented by a series of smaller folds, particularly at the lateral fringes of the valve. Histologically, the surface epithelium of the valve demonstrates a transition from the typical stratified squamous epithelium of the oral cavity to that of the respiratory epithelium lining the pharyngeal cavity. The respiratory epithelium is characterized by the presence of ciliated cells and goblet cells and is accompanied by the appearance of large mucus-secreting glands in the underlying connective tissue. The transition between the two epithelial types is marked by the presence of a relatively prominent region where the stratified squamous epithelial cells undergo a gradual transformation into the typical elements of a respiratory epithelium. SEM graphically illustrated the extent of ciliation on both components of the gular valve as well as clearly defining the transition zones between the various types of surface epithelium present. No structures resembling taste receptors were observed in the mucosa of the gular valve.

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.

Specialized veins in the submucosa of the equine ileocecal junction.

Spirally arranged bundles of sub-endothelial smooth muscle enfold the small to medium-sized submucosal veins in the equine ileocecal junction. The muscle bundles, accompanied by the endothelial lining, bulge into the lumen of the vessels, partly occluding the latter. Transmission electron microscopy of the muscle cells reveals features consistent with vascular smooth muscle ultrastructure. It is proposed that the throttling effect of the muscle bundles causes engorgement of the submucosal venous plexus, which then assists in the closing of the ileocecal orifice.

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.

Late fetal development and selective resorption in Saccostomus campestris (cricetidae).

When female Saccostomus campestris are stressed during pregnancy they may resorb part of the litter. Resorption can take place on more than one occasion during the same pregnancy without affecting the development of the rest of the litter. The last resorption may be initiated as late as 72-48 h before parturition. No other rodents with a similar gestation appear to resorb at this stage. Resorbing fetuses are isolated within uterine compartments from viable fetuses. Ossification occurs at a comparatively late stage of pregnancy in Saccostomus campestris, and there is a lag-period in fetal growth exactly 72-48 h before parturition. These factors may facilitate late resorption in this species. Factors that may cause stress in this species are most likely environmental; in the present study, dipping of the animal colony to treat for a mite infestation may have induced resorption in some of the females.

A morphological study of simple testicular cysts in the ostrich (Struthio camelus).

Simple testicular cysts are rare in mammals and of unknown aetiology, but dietary conditions have been implicated in this phenomenon in poultry. This study characterises the structural features of simple intratesticular cysts in the ostrich. Seven testes from a total of 15 sexually mature ostriches slaughtered during the breeding season were used. The testes contained multifocal, fluid-filled, unilocular cysts which were lined by a simple squamous or low cuboidal epithelium and surrounded by a thick layer of fibrous connective tissue. The cysts developed within seminiferous tubules and displayed morphological features similar to those reported in man and domestic poultry. The testis parenchyma revealed several foci composed of intermingled normal seminiferous tubules and variably sized intratesticular cysts. The atrophic tubules lay within a mass of hyperplastic, fibroblastic intertubular connective tissue in the proximity of large cysts and their formation appeared to result from hydrostatic pressure exerted by cysts. Morphological evidence supports a continuous process of cyst formation in the affected testis and a concomitant progressive loss of atrophic seminiferous tubules. A pathogenetic scenario of cyst formation and the effect of simple cysts on testicular histology has been proposed. Although the course of this phenomenon remains unknown, its impact on the fertility of this economically important bird deserves closer scrutiny.

Ultrastructure of ostrich (Struthio camelus) spermatozoa: I. Transmission electron microscopy.

The origin and relationships of the tinamous (Order Tinamiformes), ratites (Order Struthioniformes, Rheiformes, Casuariiformes, Apterygiformes) and birds of the order Galliformes and Anseriformes is the subject of much debate and it has been suggested that the ultrastructural analysis of a wide variety of avian sperm may provide information relevant to this problem. This paper describes the fine structure of ostrich sperm and compares the results with published information for other non-passerine birds. Ostrich sperm display a short, conical acrosome which covers the tapered tip of the long, cylindrical nucleus. A nuclear invagination housing an acrosomal rod extends deep within the karyoplasm. A centriolar complex is situated beneath the head and consists of a short proximal centriole and a long (3.0 microns) distal centriole which extends the complete length of the midpiece. The central cavity of the distal centriole contains a pair of microtubules embedded in a rod of electron-dense material. The midpiece is surrounded by a mitochondrial sheath. Concentrations of fine granular material are present between the mitochondria. The principal-piece of the tail is demarcated from the midpiece by a distinct annulus and characterized by a ribbed fibrous sheath enclosing a typical axoneme. Rudimentary coarse fibres are observed between the fibrous sheath and the doublet microtubules of the axoneme in the proximal region of the principal-piece. The end-piece contains a disorganized collection of axonemal microtubules. Ostrich sperm differ in a number of respects from that of other non-passerine birds (the absence of a typical perforatorium; the presence of a ribbed fibrous sheath; a deep nuclear invagination; the structure and length of the distal centriole) but show a close similarity to sperm of the rhea and crested tinamou, both representatives of primitive avian families. These observations add further support to the theory that the ratites and tinamous constitute a monophyletic group. The evidence presented also reinforces the hypothesis that the ratites were the first group to branch off from the main avian stem, to be followed by the Galliformes & Anseriformes. Although it was impossible to determine whether the sperm of the tinamou are more "primitive" than those of the ostrich or rhea, it is clear that ostrich and rhea sperm are closely allied and distinct from tinamou sperm.

Ultrastructure of ostrich (Struthio camelus) spermatozoa. II. Scanning electron microscopy.

The three-dimensional structure and size of ostrich sperm is unknown. In this study, the morphology and dimensions of ostrich sperm were determined by scanning electron microscopy of semen samples obtained from sexually mature males during the breeding season. The results indicate that sperm cells of the ostrich are of the sauropsid type characteristic of non-passerine birds and, in general appearance, resemble those of the chicken, turkey, guinea fowl, budgerigar and tinamou. They differ from tinamou sperm, however, in that they do not show a small bump at the tip of the acrosome. Ostrich sperm are shorter (69.6 microns total length) than those of the chicken, turkey and guinea fowl, but longer than those of the budgerigar. A lack of information makes it impossible to compare the dimensions of ostrich sperm with those of other ratites such as the rhea. In ostrich and guinea fowl, the sperm head is proportionately longer than that of the chicken, turkey and budgerigar as determined by tail to head ratios. Two distinct groups of ostriches could be distinguished on the basis of differences in the length of various sperm cell components. This may reflect persistent genetic (subspecies) variations in the domestic ostrich population.

General morphology of the oral cavity of the Nile crocodile, Crocodylus niloticus (Laurenti, 1768). II. The tongue.

The heads of nine 2.5 to 3-year-old Nile crocodiles (Crocodylus niloticus) were obtained from a commercial farm where crocodiles are raised for their skins and meat. The animals from which these specimens were obtained appeared clinically healthy at the time they were slaughtered. A description of the macroscopic and microscopic features of the tongue of the Nile crocodile is presented and the results are compared with published information on this species and other Crocodylia. The histological features are supplemented by information supplied by scanning electron microscopy. Macroscopic features of interest were the dome shaped structures grouped in a triangular formation on the posterior two-thirds of the dorsum of the tongue. These structures were identified by light microscopy to contain well-developed branched, coiled tubular glands and associated lymphoid tissue. Other histological features included a lightly keratinised stratified squamous surface epithelium supported by a thick layer of irregular dense fibrous connective tissue. Deep to this region was a clearly demarcated adipose tissue core with a dense mass of striated lingual musculature. Localised thickenings were present in the epithelium which were associated with ellipsoid intra-epithelial structures resembling taste buds.

Scanning electron and light microscopy of the mucosa of the equine ileocaecal junction.

The ileocaecal junction mucosal surface morphology of 5 horses and 1 donkey was examined using scanning electron microscopy and light microscopy. Based on differences in surface morphology, the junction could be divided into 4 distinct regions. The distal extremity of the ileum was characterized by the presence of typical finger-like villi followed by a narrow zone displaying short, stubby villi which gradually merged into a 3rd region representing the true transitional zone between the small and large intestine. In this region the villi fused, forming low ridges arranged in circular, semi-circular or S-shaped patterns. Many of the fused villi were indented at the tips giving these structures a doughnut-like appearance. The caecal portion of the ileocaecal junction formed the 4th region and was characterized by the absence of villi and the occurrence of regularly spaced crypt openings each surrounded by a slightly raised circular mound.