The Sertoli cell of the water buffalo--an electron microscopic study.

The ultrastructure of Sertoli cells in the seminiferous tubules of water buffaloes before and during sexual maturity was studied by transmission electron microscopy, with emphasis on the intranucleolar vesicular elements. Sertoli cells of animals under 12 months of age were distinguished from the germ cells by the presence of electron dense membrane bound bodies within their cytoplasm. These cells, referred to as basal indifferent supporting cells, were probably involved in the phagocytosis and elimination of degenerating spermatocytes, which failed to differentiate into spermatids and spermatozoa in animals under one year of age. In 12 month old animals, a few Sertoli cells exhibiting the vesicular elements appeared in the nucleolar region while in animals over 15 months of age Sertoli cells could be positively identified by the characteristic cytoplasm containing microtubules, elongated and electron dense mitochondria, extensive granular endoplasmic reticulum and the presence of spermatids in various stages of spermiogenesis. The vesicular elements in the nucleolar region of the Sertoli cells were most prominent at this stage. Ultrastructural features of the Sertoli cells revealed an abundance of ribosome-like particles surrounding the vesicles of varying size. Some of these vesicular elements contained amorphous material suggesting that they represent the products sequestered in the nuclear region for transport to the cytoplasm and that the process of spermiogenesis may be dependent on the ability of Sertoli cells to generate these products at sexual maturity.     

Alterations in the immunohistochemical localization patterns of alpha-smooth muscle actin (SMA) and vimentin in the postnatally developing bovine cryptorchid testis

Previously, we reported the normal postnatal developmental changes in immunohistochemical localization of alpha-smooth muscle actin (SMA) and vimentin in the bovine testis. In this study, we demonstrate the alterations of these cytoskeletal proteins in the bovine cryptorchid testis as compared to the contralateral scrotal testis during postnatal development. Seminiferous peritubular alpha-SMA did not appear in the cryptorchid testis until 8 months of age, except for very weak intermittent filaments in relatively larger seminiferous tubules. However, a similar peritubular pattern was observed in the 18-month-old cryptorchid and scrotal testes. Moreover, weak expression of alpha-SMA in the straight tubules and rete testes at 5 months of age did not improve until 18 months of age in the cryptorchid testes. The Sertoli cell vimentin in the cryptorchid testes revealed a highly immature pattern at 5 months of age, a pattern similar to a transforming pattern with infranuclear vimentin extensions at 8 months of age, and a pattern that was almost a transforming pattern, but with considerable weakening of the vimentin filaments, at 18 months of age. In conclusion, cryptorchidism may cause considerable delay in testicular myoid cell differentiation and in attainment of the transforming pattern of the Sertoli cell vimentin, which weakens and fails to attain the mature pattern in the cryptorchid testis. These alterations may be related to the structural immaturity and functional failure of postnatally developing bovine testes exposed continuously to body heat.     

Ultrastructure of goat testes: tubulobulbar complexes between spermatids and Sertoli cells

The fine structure of tubulobulbar complex (TBC) of goat seminiferous epithelium was studied using testicular samples fixed by perfusion. During the maturation phase of the spermatid, the TBC appeared on the periphery of the head before spermiation, dorsal and ventral parts of the head, both sides of the acrosome and on the postnuclear sheath region. At an early stage of the development of the TBC, a partial loss of smooth endoplasmic reticulum in the ectoplasmic specialization of a neighboring Sertoli cell was observed; filament bundles disappeared and a small fragmented smooth endoplasmic reticulum was left. Subsequently, a spermatid vesicle (coated vesicle) expanded to be in contact with the Sertoli cytoplasm by a small channel. These tubular projections extended to form a bulbous balloon-like structure forming sometimes a bi-balloon appearance, until torn off from the spermatid into the Sertoli cytoplasm and probably digested by the Sertoli cell. The significance of this structural development was morphologically discussed.     

Microstructure Features of Proventriculus and Ultrastructure of the Gastric Gland Cells in Chinese Taihe Black‐bone Silky Fowl (Gallus gallus domesticus Brisson)

To investigate microstructure of proventriculus and ultrastructure of the gastric gland cells from Chinese Taihe black‐bone silky fowl (BSF), the proventriculus of 4‐week‐old BSF was sampled. Conventional histological and transmission electron microscope (TEM) methods were used in this study. The wall of the Taihe BSF proventriculus was consisted of four layers, the mucous, submucosa, muscularis externa and the serosa as others birds. The muscularis externa of the birds' proventriculus contained three layers. Much of the melanin was present in loose connective tissue of lamina propria, submucosa, and muscularis externa unlike others. In addition, the ultrastructure of the gastric gland cells was observed by TEM. There was only one kind of gland cell, for example oxynticopeptic cell in proventriculus of Taihe BSF. The oxynticopeptic cells contained numerous mitochondria, cisternae of rough endoplasmic reticulum (CRER), intracellular canaliculi (IC) that secrete hydrochloric acid and small amounts of pepsinogen granules. The rough endoplasmic reticulum (RER) was irregular cisternae with ribosomes and surrounded tightly the mitochondria along their configuration. The electron‐dense pepsinogen granules were round with various sizes. The neighbouring oxynticopeptic cells were closed up with tight junction and gap junction. The inter‐space between the neighbouring oxynticopeptic cells was stenosis or was filled with electron‐dense extracellular substance. In conclusion, the gastric gland cells of Chinese Taihe BSF proventriculus were only oxynticopeptic cells that secrete hydrochloric acid and pepsinogen, but no parietal cells and chief cells of mammal. The gastric gland cells of proventriculus were underdeveloped compared with those of mammals.     

Entry and intracellular localization of Brucella spp. in Vero cells: fluorescence and electron microscopy

Vero cells were inoculated with the six species of Brucella (B. abortus, B. melitensis, B. suis, B. neotomae, B. canis, and B. ovis) and examined by fluorescence and electron microscopy. All Brucella spp. were internalized by Vero cells. In all cells except those inoculated with B. canis, the numbers of intracellular brucellae increased with time after inoculation. Intracellular brucellae were first seen within phagosomes and phagolysosomes. Subsequent localization within cisternae of the rough endoplasmic reticulum was seen with all species of Brucella, except B. canis, which was restricted to phagolysosomes. Although rough brucellae were more adherent and entered a greater number of Vero cells, intracellular replication occurred in a larger percentage of cells with smooth rather than with rough brucellae. These results suggest that phagocytosed Brucella spp. are transferred 1) to cisternae of the rough endoplasmic reticulum, where unrestricted bacterial replication takes place; or 2) to phagolysosomes in which Brucella spp. fail to replicate. The various strains of Brucella spp. differ in their ability to induce their own transfer to the rough endoplasmic reticulum.     

Ultrastructure of the thyroid gland of the one-humped camel (Camelus dromedarius)

Follicular epithelium of the thyroid gland of the one-humped camel was examined by light and electron microscopy. It consisted of a single type of epithelial cell which varied from flattened to columnar in shape. Follicular epithelial cells were characterized by the presence of markedly dilated cisternae of rough-surfaced endoplasmic reticulum, well developed Golgi apparatus, abundant small vesicles (150 nm to 200 nm in diameter) in the apical cytoplasm, and electron-dense colloid droplets measuring from 250 nm to 1600 nm. Follicular epithelial cells frequently showed apocrine secretion into colloidal lumens. Apocrine protrusions with smooth surface were dome-like or balloon-like structures and contained a fine granular matrix. These findings indicate that the morphological features of the follicular epithelial cells of the thyroid gland of the camel are essentially similar to those of mammals except for the presence of apocrine secretion, which is unique to the camel.     

Fasciola hepatica: a light and electron microscope study of sustentacular tissue and heterophagy in the testis

In order to investigate cytolytic activity in the testis of Fasciola hepatica, flukes belonging to several different triclabendazole (TCBZ)-sensitive and TCBZ-resistant isolates, and wild-type flukes from field infections, were studied by light and electron microscopy with a view to identifying sites of heterophagy and macromolecular hydrolysis. At the periphery of the testis tubules in all the flukes examined, large euchromatic nuclei, each bearing a prominent nucleolus, were seen. These were invested with a thin cytoplasmic layer, extensions of which partially enveloped and probably supported the neighbouring spermatogonia. No lateral cell boundaries were identified in this tissue, possibly indicating syncytial organisation. The tissue, considered to be analogous to Sertoli cells in vertebrate testis, was identified as sustentacular tissue. It displayed cytoplasmic features consistent with protein/glycoprotein synthesis (through a granular endoplasmic reticulum-Golgi mediated mechanism) and intracellular digestion/heterophagy (through a lysosomal system). The intracytoplasmic hydrolytic activity of the sustentacular tissue probably serves to scavenge effete cells and cytoplasmic debris, to recycle useful molecules, to promote spermatozoon maturation and possibly to aid osmoregulation within the tubules. Certain protein-containing macromolecules synthesised in the sustentacular tissue may contribute to the seminiferous fluid, or have pheromonal activity. The presence of numerous mitochondria and abundant smooth endoplasmic reticulum is consistent with facilitation of inward and outward movement of micromolecular nutrients, metabolites including excretory products and water. In the sustentacular tissue of certain flukes with dysfunctional spermiogenesis, there was increased heterophagic and cytolytic scavenging activity. The cytoplasmic residual vacuoles remaining after the release of spermatids were also identified as possible sites for lysosome-mediated intracellular digestion and osmoregulation in the testis tubules of F. hepatica.     

Expression of Occludin in Canine Testis and Epididymis

Tight junctions (TJ) in inter-Sertoli junctional areas and epididymal epithelia are important for the formation of blood-testis barrier (BTB) and blood-epididymal barrier (BEB). In this study, the expression of occludin, an integral member of the TJ, was verified in canine testis and epididymis. Both low molecular weight (MW) (25-28 kDa) forms as well as high MW (68-72 kDa) forms of occludin were detected in the testis and epididymis using Western blot. The relative amount of the high MW forms of occludin vs low MW forms was higher in the testis than in the epididymis. Some difference in the composition of different MW forms of occludin was found along the segments of epididymis, suggesting the possible correlation between cellular composition of occludin proteins and paracellular permeability of epithelia along the epididymal tubule. In the testis, intense occludin immunoreactivity was found in the basally located inter-Sertoli junctional area. Diffused immunoreactivity of occludin was also found in the cytoplasm of Sertoli cells. A similar pattern of zonula occludens-1 immunoreactivity was found in the cytoplasm of Sertoli cells, suggesting that occludin was not confined to the inter-Sertoli junctional areas and that subcellular localization of occludin in the Sertoli cells was dynamically regulated during spermatogenesis in canine testis. In the epididymis weak immunoreactivity was found in the apical sides and cytoplasm of epithelial cells.     

Closure of the ductus arteriosus of indigenous South African goats at high altitude

The closure of the ductus arteriosus (DA) of 31 indigenous South African goats, whose ages ranged from 30 days prenatal to 60 days postnatal, were studied at an altitude of 1,514 m above sea level by vascular injection as well as histologically and ultrastructurally. The vascular injection results showed that functional occlusion started from the pulmonary end of the DA in kids 6 days old and progressed to the aortic end in kids 8 days old. Histologically, anatomical obliteration was observed in kids from 35 days of age. The functional closure was preceded by enlargement of the subendothelial region, progressive intimal thickening, presence of subendothelial vacuolization and endothelial detachment. There was radial orientation of the subintimal smooth muscle cells and subsequent migration towards the intima. The inner tunica media contained mast cells and areas of cytolysis. Following functional closure, the subendothelial region showed migrating subintimal smooth muscle cells with extensive cytoplasmic processes and, ultrastructurally a fragmented internal elastic lamina. In 15-day-old kids there were prominent, progressively enlarged cisternae of the rough endoplasmic reticulum and numerous free, dispersed ribosomes. In kids 19 and 25 days old, there was, additionally, rarefaction of the cell cytoplasm and appearance of intracellular myofibrils and extra cellular collagen in the surrounding amorphous matrix, which culminated in the complete anatomical closure of the DA in 35-day-old kids.     

Ultrastructural study of sheep lacrimal glands.

Sheep lacrimal glands are mixed glands, consisting of tubulo-acinar units succeeded by ducts of simple morphology. The secretory portions consist of three cell types: mucous, seromucous and serous, which may be intermingled in the same acinus or may form acini wholly made of only serous or mucous cells. Mucous cells show a rough endoplasmic reticulum that is reduced to a few cisternae located near the cell base and among the interstices of the secretory droplets. Mucous granules appear uniformly electron-lucent. Serous cells display a typical structure; serous granules can be uniformly electron-dense or composed of dense inclusions dispersed in an electron-lucent matrix. The seromucous granules have a bizonal substructure: a dense core is embedded in a highter matrix. Secretory acini are succeeded by intercalated ducts; the epithelium of these ducts gradually increases in height to form a kind of excretory duct, without the intervention of striated ducts.     

Testicular torsion in the dog: a review of 13 cases.

The clinical and pathological features of testicular torsion in 13 dogs are reviewed. The affected gonads were intra-abdominal in 11 animals, and inguinal and scrotal respectively in two others. In most cases, the torsion appeared to result from neoplastic enlargement of the testis.     

Malignant Sertoli Cell Tumour in a Young Simmenthal Bull – Clinical and Pathological Observations

Tumours are rare in the bovine testicle. A case of malignant Sertoli cell tumour in a 29‐month‐old Simmenthal bull that was hospitalized with a history of severe unilateral scrotal swelling is reported. On inspection and palpation, the scrotal sac was found enlarged with fluctuant content in the right side. The right testicle was enlarged, hard and indolent. Also the right plexus pampiniformis and funiculus spermaticus were enlarged. Sonograms revealed severe changes in the right testicle with a loss of homogeneity and multiple hyperechogenic areas. After slaughter, the scrotum with testicles were removed and evaluated pathologically. On section, the right testicle contained areas of necrosis, haemorrhage, and mineralization. Histology showed Sertoli cells in tubular structures surrounded by dense fibrous stroma replacing normal testicular tissue. Both lymphatic and blood vessels were infiltrated by neoplastic cells. Immunohistochemically, the neoplastic cells stained positive for vimentin and negative for cytokeratin and S‐100. Based on the pathological observations a diagnosis of right‐sided malignant Sertoli cell tumour with vascular invasion and hydrocele was established.     

Ultrastructural and ultracytochemical cyclic changes in the bovine uterine tube (oviduct) epithelium.

Ultrastructural and ultracytochemical features of the uterine tube (oviduct) infundibulum were studied in 8 Hereford cows, which were slaughtered in pairs on days 1 (estrus), 3, 9 or 10, and 18 of the estrous cycle. Fibrous granules (60 to 80 nm), which are supposedly related to basal body replication, were observed in the apical cytoplasm of ciliated cells. Close association between basal bodies and fibrous granules was apparent, especially during the follicular phase. Cilia were observed throughout of estrous cycle, although degeneration of cilia was not observed at any phase of the cycle. Prominent, striated rootlets were observed during both the follicular and luteal phases of the cycle. Maximum secretory cell differentiation was apparent during the follicular phase, at which time these cells were characterized by having a well-developed, rough endoplasmic reticulum with dilated cisternae, numerous ribosomes, and secretory granules of varied size and density. A prominent feature of the secretory granules was their membranous structure, consisting of concentric lamellae of equal dimensions. During the luteal phase, cytoplasmic protrusions were prominent, and extruded nuclei along with other cytoplasmic organelles were present in the tubal lumen. The presence of a well-developed, rough endoplasmic reticulum and numerous secretory granules during the follicular phase indicates that secretory activity of the uterine tube infundibulum may be stimulated by estrogen. During estrus, the cytoplasm of the stromal cells displayed abundant, rough endoplasmic reticulum with dilated cisternae. The increased and extensively dilated rough endoplasmic reticulum at the time of estrus probably indicates increased protein synthesis by the stromal cells. The presence of adenosine triphosphatase activity on the membrane of cilia suggests that this enzyme is involved in energy-forming reactions related to the vigorous action of cilia. The presence of acid phosphatase activity on the cell membrane of the epithelium, microvilli, and secretory granules may indicate involvement in the secretory mechanism of the cell.     

Histological Characterization of Defective Spermatogenesis in Mice Lacking the Basigin Gene

Basigin is a transmembrane protein belonging to the immunoglobulin superfamily. In the light of the fact that knockout mice lacking the basigin gene (Bsg) are azoospermic, the phenotype in the male reproductive system was extensively examined in this study. Spermatogenesis in Bsg (-/-) mice was found to be disrupted, and arrested at the metaphase of the first meiotic division. A few germ cells differentiated into young spermatids, but they were exfoliated. The lumens of the male reproductive system were filled with round degenerated cells. Using the TUNEL method and electron microscopy, some of the degenerated cells in the testis and epididymal head were shown to be apoptotic. Crystalloids of fine tubules and unusual ectoplasmic specializations were also observed in the Sertoli cells of Bsg (-/-) mice. These specializations displayed unusual 'circular' structures. Furthermore, unusual ectoplasmic specializations covering the spermatocytes rather than the mature spermatids were found. These structures were formed as a result of the lack of mature spermatids in the Bsg (-/-) testis. Results from analyses of azoospermia in the Bsg (-/-) mice suggest that basigin, through the interactions between germ cells and Sertoli cells, is an essential factor in the growth and/or survival of spermatids.     

Ultrastructural Morphology of Plasma Cells in Normal Ovine Hemal Lymph Nodes

The fine structure of plasma cells from the hemal lymph nodes of five healthy sheep was examined. The plasma cells showed many cytoplasmic processes, indicating motility and phagocytic activity. They were randomly located in the medullary cords of the hemal lymph nodes. Their perinuclear spaces were irregular and contained granular material similar in density to that of rough endoplasmic reticulum. Some of the plasma cells provided morphological evidence of erythrophagocytosis at different levels. Such a phenomenon was previously reported only in pathological conditions. The red blood cell being engulfed by the plasma cell appeared smaller than normal. Most of the examined plasma cells showed Russell's Bodies inside the cisternae of the rough endoplasmic reticulum of the healthy hemal lymph nodes. Some of these Russell's Bodies had fuzzy borders. They were separated from the rough endoplasmic reticulum by evenly spaced halos.
Many plasma cells showed physical contacts with mast cells in the form of cell junctions, and some showed cytoplasmic continuity between the two cells. Such relations have been discussed in this article.     

Pubertal Development of Intersertoli Cell Junctions in the Testis of Corriedale Ram Lambs

The ultrastructure of the tight junctional complex of pubertal ram lamb Sertoli cells was studied in immersion-fixed samples and related to clinical data and a light microscopical classification of the degree of spermatogenesis attained in the corresponding seminiferous tubule. Although the process followed the general mammalian developmental trend for tight junction complex formation, 2 unusual ultrastructural features were detected: the presence of an active Golgi complex during the early stage of tight junction formation and the transitory presence of ribosomes on both faces of the ectoplasmic cisternae bordering the developing junctions. The significance of these findings is discussed.     

Comparisons of endocrinological and testis parameters in 18-month-old Ile de France and Romanov rams

Endocrinological and testis parameters of adult 18-month-old Ile de France (IF) and Romanov (Ro) rams were compared during sexual season. Testis weights, total volumes of intertubular tissue, and of blood and lymph vessels, total seminiferous tubule length, rete testis flow rate and daily production of germ cells were significantly higher in IF than in Ro rams. These variations originated from differences in Sertoli cell numbers, which were established before puberty. When daily productions of germ cells, of ABP or of RTF were expressed per Sertoli cell, they were higher in Ro than in IF rams. Quality of spermatids, as measured by their cellular size prior to elongation, was lower in Ro than in IF. The number of FSH-binding sites per Sertoli did not differ between the two breeds but FSH plasma levels were higher in Ro than in IF rams. Total numbers of Leydig cells per testis, their individual size or their LH-binding capacity did not differ significantly between the two breeds. However, the ratio of mean testosterone upon mean LH plasma levels were greater in Ro than in IF rams while both breeds had identical LH mean plasma levels.     

Structure of cultured fibroblasts from dermatosparaxic calves.

Clonal cell lines from the dermis of a dermatosparaxic calf were grown in tissue culture. After fixation in a mixture of glutaraldehyde and osmium, they were prepared for electron microscopy. Most cells contained a well-developed Golgi region, lysosomes, mitochondria, and dilated cisternae of rough endoplasmic reticulum. They also contained numerous, large bundles of intracellular fialments, many lipid droplets and extensive arrays of vesicles. Cultures accumulated substantial amounts of extracellular fibrillar material. The fibrils were loosely packed and indistinctly cross-banded. Bundles of intracellular filaments were commonly parallel in adjacent cells and also parallel to extracellular fibrils. These cytoplasmic features may result from the inability of the secreted collagen to form normal fibrils.     

Malignant Mixed Sex Cord-stromal Tumour in a Stallion

A 30-year-old Standardbred stallion was examined for unilateral scrotal swelling. Physical and ultrasound examinations revealed a painless enlarged left testis with a non-homogeneous echogenicity, when compared with the controlateral testis. The stallion underwent left unilateral orchiectomy. Grossly, the excised testis was irregularly enlarged (12 x 9 x 9 cm; weight: 530 g) and firm. The sections showed that testicular parenchyma was replaced by a lobulated, greyish-white mass, which involved the epididymal head. At microscopy, a dual Leydig and Sertoli cell tumour component could be seen. Neoplastic Sertoli cells were prevalent and presented pleomorphic cells, mitotic figures and occasional vascular invasion. Tumour patterns showed tubular and solid areas, cord-like or diffuse in appearance, among which newly formed Leydig cell nests and low-density fibrillar bundles were interposed. Immunohistochemically, a weak to moderate immunostaining for vimentin, AE(1)/AE(3) cytokeratin, alpha-1-antitrypsin and CD99 antigens was found in the growing Sertoli cells, whose nuclear MIB-1 labelling index scored 13 +/- 2%. The Leydig tumour cells, on the other hand, displayed a moderate to strong positivity for alpha-inhibin, vimentin, AE(1)/AE(3) cytokeratin, neurone-specific enolase and CD99. On the basis of these findings, a diagnosis of malignant mixed sex cord-stromal tumour was made.     

SONOGRAPHIC EVALUATION OF CANINE TESTICULAR AND SCROTAL ABNORMALITIES: A REVIEW OF 26 CASE HISTORIES

The ultrasonographic and medical records of 26 dogs examined for testicular/scrotal abnormalities were reviewed. Fifteen dogs were diagnosed with testicular neoplasia that included one or more of the following tumor cell types: Sertoli cell, seminoma and interstitial cell. Ultrasound was highly sensitive to detection of testicular neoplasia including one nonpalpable tumor. Tumor type specificity was not readily apparent in this study, although the three nondescended Sertoli cell tumors displayed similar characteristic sonographic patterns. Six dogs were reviewed with nonneoplastic, noninfectious disorders that included: vascular compromise, atrophy, scrotal edema and intestinal hernia. Five dogs with infectious diseases were reviewed. Ultrasound was sensitive and relatively specific for the nonneoplastic conditions.