P.C. Ozegbe

The testicular capsule and peritubular tissue of birds: morphometry, histology, ultrastructure and immunohistochemistry

The testicular capsule was studied histologically, morphometrically, ultrastructurally and immunohistochemically in the Japanese quail, domestic fowl, turkey and duck (all members of the Galloanserae). The testicular capsule was, relative to mammals, thin, being 81.5 ± 13.7 µm in the quail, 91.7 ± 6.2 µm in the domestic fowl, 104.5 ± 29.8 µm in the turkey and 91.8 ± 18.9 µm in the duck. The orchido‐epididymal border (hilus) of the capsule was much thicker than elsewhere in all birds (from 233.7 ± 50.7 µm in the duck to 550.0 ± 147.3 µm thick in the turkey). The testicular capsule, other than the tunica serosa and tunica vasculosa, comprised, in the main, smooth muscle‐like or myoid cells running mainly in one direction, and disposed in one main mass. Peritubular tissue was similarly composed of smooth muscle‐like cells disposed in several layers. Actin and desmin intermediate filaments were immunolocalized in the inner cellular layers of the capsule in the quail, domestic fowl and duck, but uniformly in the turkey. Vimentin intermediate filament immunoreaction in the capsule was moderately and uniformly positive in the testicular capsule of only the quail. Actin and desmin, but not vimentin (except very faintly in the turkey) or cytokeratin, were immunolocalized in the peritubular tissue of all birds. The results therefore establish, or complement, some previous observations that these birds have contractile cells in their testicular capsule and peritubular tissue, whose function probably includes the transport of testicular fluid into the excurrent duct system.

Immunohistochemistry of the cytoskeleton in the excurrent ducts of the testis in birds of the Galloanserae monophyly

The presence, location and degree of immunoexpression of various microfilament (MF) and intermediate filament (IF) systems (actin, cytokeratins, desmin, vimentin) were studied in the excurrent ducts of the testis in sexually mature and active galliform (Japanese quail, domestic fowl, turkey) and anseriform (duck) birds. These proteins were variably expressed between the epithelia and periductal tissue (periductal smooth muscle cell layer and interductal connective tissue) types and between species. Variable heterogeneous co-expression of filament systems was also found in the various duct epithelia and periductal tissue types: co-expression of filament systems was the rule rather than the exception. In the duck, neither vimentin nor cytokeratin was present in any of the tissues, whereas actin and desmin (absent in the rete testis) were co-expressed in the efferent ducts and epididymal duct unit (comprising the ductus conjugens, ductus epididymidis and ductus deferens). Actin, desmin and vimentin were generally co-expressed in the rete testis, efferent ducts and epididymal duct unit of the quail, domestic fowl and turkey, with vimentin being more strongly immunoreactive than actin and desmin in the epididymal duct unit, but more weakly immunoexpressed in the efferent ducts. Cytokeratin was present and co-expressed with actin, desmin and vimentin in the rete testis, efferent ducts and epididymal duct unit of the domestic fowl and turkey, but not in the quail and duck. The periductal smooth muscle cell layer and interductal tissue co-expressed actin, desmin and vimentin variably in all birds. Luminal spermatozoa of both the turkey and duck were immunonegative for all protein systems, whereas those of the quail and domestic fowl co-expressed actin, desmin and vimentin moderately or strongly. The tissues of the reproductive tract of male birds thus contain cytoskeletal protein systems that are variably but mostly co-expressed and whose contractile ability appears necessary and sufficient for transportation through the various excurent ducts of the voluminous testicular fluid and its high sperm content, characteristic features of male avian reproduction.

The excurrent ducts of the testis of the emu (Dromaius novaehollandiae) and ostrich (Struthio camelus): microstereology of the epididymis and immunohistochemistry of its cytoskeletal systems.

The volumetric proportion of the various ducts of the epididymis of the emu and ostrich and the immunohistochemistry of actin microfilaments, as well as cytokeratin, desmin and vimentin intermediate filaments, were studied in the various ducts of the epididymis of the emu and ostrich. The volumetric proportions of various ducts, which are remarkably different from those of members of the Galloanserae monophyly, are as follows: the rete testis, 5.2 ± 1.4% for the emu and 2.4 ± 1.8% for the ostrich; efferent ducts, 14.2 ± 2.3% (emu) and 11.8 ± 1.8% (ostrich); epididymal duct unit, 25.8 ± 5.8% (emu) and 26.1 ± 4.1% (ostrich) and connective tissue and its content, 54.7 ± 5.8% (emu) and 60.0 ± 4.9% (ostrich). Unlike in mammals and members of the Galloanserae monophyly, only vimentin was immunohistochemically demonstrated in the rete testis epithelium of the emu, and none of the cytoskeletal protein elements in the ostrich rete testis. The epithelium of the efferent ducts of the emu co‐expressed actin, cytokeratin and desmin in the non‐ciliated type I cells, and vimentin in the ciliated cell component. The ostrich demonstrated only cytokeratin in this epithelium. The ratite epididymal duct unit is different from that of mammals in lacking actin (only weaky expression in the ostrich), desmin and cytokeratin, and a moderate/strong immunoexpression of vimentin in the basal cells and basal parts of the NC type III cell in the epididymal duct unit. Immunoexpression of the microfilaments and intermediate filaments varied between the two ratite birds, as has been demonstrated previously in birds of the Galloanserae monophyly, and in mammals.

Components and development of the centriolar complex during and beyond spermiogenesis in a passeridan bird, the Masked weaver (Ploceus velatus).

The fate of the proximal centriole in passeridan birds is an area of controversy and relative lack of knowledge in avian spermatogenesis and spermatology. This study examines, for the first time, spatiotemporal changes in the centriolar complex in various phases of spermiogenesis in a passerine bird, the Masked weaver (Ploceus velatus). It also describes the configuration of the centriolar complex and the relationship between it and the granular body in both intra- and extra-testicular spermatozoa. It is shown that the proximal centriole is retained and attaches, at its free end, to the granular body of spermatids in every step of spermiogenesis, as well as in mature intra-testicular and post-testicular spermatozoa, including those in the lumen of the seminal glomus. As the centriolar complex, along with its attached granular body, approaches the nucleus in the early spermatid, the proximal centriole articulates with the distal centriole at an acute angle of about 45°, and thereafter, both centrioles, still maintaining this conformation, implant, by means of their articulating proximal ends, at the implantation fossa of the nucleus. In the mature spermatid and spermatozoon, the granular body winds itself helically around the centriolar complex in the neck/midpiece region of the cell, and, thus, becomes the granular helix. The significance of this observation must await future studies, including possible phylogenetic re-evaluation and classification of birds.

Structural and Immunohistochemical Features of the Epididymal Duct Unit of the Ostrich (Struthio camelus)

The epididymal duct unit, comprising the ductus conjugens, ductus epididymidis and ductus deferens, was studied histologically, ultrastructurally and immunohistochemically in five sexually mature and active birds. The main morphological features of the pre‐dominant non‐ciliated (type III) cell of the epithelial lining of this duct unit include, but are not limited to, a moderately abundant smooth or sparsely granulated endoplasmic reticulum, electron‐dense secretory granules and numerous mitochondria in the supranuclear zone of the cytoplasm. A single, large heterogeneous lipid droplet, of unknown function, was characteristically situated immediately proximal to the nucleus. The epithelium is obviously secretory and specifically, of the merocrine, and not apocrine, type of secretion. The epithelium of the epididymal duct unit was only focally and weakly to moderately immunopositive to both actin MF and desmin IF, while the duct unit was immunonegative to cytokeratin and vimentin intermediate filaments. The peritubular muscular layer was moderately to strongly positive to both actin and desmin, and negative to cytokeratins and vimentin.

The cytoskeletal proteins in the contractile tissues of the testis and its excurrent ducts of the passerine bird, Masked Weaver (Ploceus velatus).

The cellular composition of the testicular capsule, seminiferous peritubular tissue, the epithelia as well as periductal muscle cell layers of the excurrent ducts was studied, in sexually mature and active Masked Weaver (Ploceus velatus) birds of the passerine family, Ploceidae. Ultrastructure of the contractile cells in the testicular capsule, peritubular and periductal tissues showed that these cells were smooth muscles of typical morphological characteristics. Variability in the immunohistochemical co-expression of microfilaments and intermediate filaments in the different tissues was evident. Actin and desmin proteins were co-expressed immunohistochemically in the testicular capsule and seminiferous peritubular smooth muscle layer. Actin was singly and very weakly expressed in the rete testis epithelium while cytokeratins and desmin were co-expressed in the epithelium of the excurrent ducts. The periductal muscle layer of all ducts of the epididymis, the ductus deferens as well as the seminal glomus, strongly co-expressed actin and desmin. Vimentin was absent in all cells and tissue types studied. There is clear evidence that the tissues of the male gonad and its excurrent ducts in the Masked Weaver, as has been reported for members of the Galloanserae and Ratitae, contain well-formed contractile tissues whose function would include the transportation of luminal through-flow from the testis into, and through, its excurrent ducts. The microtubule helix in the head and of the mid-piece, of elongating spermatids, as well as of the mature spermatozoa in the various excurrent ducts, including some spermatozoa in the seminal glomus, also co-expressed these three proteins.

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.

A rare case of left additional renal artery in a Nigerian goat

The report of the occurrence of additional renal arteries in domestic animals is rare in the literature. We report a case of an additional renal artery in the left kidney found in a Red Sokoto goat cadaver. The additional renal artery originated from the abdominal aorta 3.80 cm cranial to the origin of the main renal artery. The additional renal artery was relatively long, being 6.30 cm from its origin to the cranial pole region of the kidney where it supplied the kidney. This to the best of our knowledge is the first report in the literature indexed in the Medline of an additional renal artery in a goat.