Zur funktionellen Morphologie des Rete testis, der Tubuli recti und der Terminalsegmente der Tubuli seminiferi des geschlechtsreif en Rindes1,2

The functional morphology of the rete testis, tubuli recti and terminal segments of the tubuli seminiferi in the mature bull The terminal portion of the seminiferous tubule in the mature bull has three segments: a transitional segment, a middle segment and a terminal plug. The middle segment and the terminal plug are formed almost exclusively by modified sustentacular cells. Each terminal segment is surrounded by a cuff-like, vascular plexus. The seminiferous tubule is succeeded by the straight tubule. The latter begins with a funnel-shaped enlargement which surrounds the terminal plug and then forms a smooth-walled, narrow tube that could be likened to the stem of the funnel. The tubular segment between the stem of the funnel and the rete is characterized by intraepithelial invaginations. The single layer of epithelium of the straight tubule and of the rete contains large numbers of free cells (lymphocytes and macrophages) which constitute up to 25 % of the epithelium. In the subepithelial stroma of the rete are free elastic fibers and flat cells which, because of their phosphatase content, are thought to be contractile.     

The mammalian rete ovarii: a literature review

The rete ovarii is the homologue of the rete testis. It develops from cells of mesonephric origin which immigrate into the developing gonad of the embryo. The mature form of the rete ovarii is generally found to be groups of anastomosing tubules lined by cuboidal or columnar epithelium. These tubules are usually located in the hilus of the ovary, but may extend through the medulla or be isolated in the mesovarium adjacent to the hilus. The rete is often continuous with the transverse ductules through which it contacts the longitudinal duct of the epoophoron. The rete ovarii is important in the control of meiosis in the maturing ovary. Cells of the rete ovarii differentiate to form granulosa cells as well. The rete is also credited with secretory capability, a hypothesis supported by the observation of secretory material in the lumina of the rete tubules in several species. Cysts have been observed in the rete ovarii of several species. The rete ovarii of the adult does not appear to be a functionless vestige as has been previously reported.     

Histomorphometrische und histologische Untersuchungen zur morphokinetischen Wirkung von Furazolidon auf die Spermiogenese geschlechtsreifer Ratten

The antispermatongenic effects of furazolidone on the testes of mature Wistar rats were investigated using histological and morphometric methods. The sections showed a varying degree of depopulation of the germinal epithelium, a shrinking and a deformation of the Tubuli contorti, and an enlargement of the intertubular lymphatic sinuses. The strain led to a standstill in the spermatogenesis at the primary-spermatocyte stage. After administering furazolidone, the following results could be seen: – a weightloss of up to 42.1% and a decrease in testes volume by up to 30.2% – a decrease in the volume of the nuclei of the Leydig-cells by up to 51.6% – a reduction in the diameter, perimeter and area covered by Tubuli seminiferi contorti of up to 33.5%, 30.8%, and 53.4%, respectively – an increase in the number of Tubuli seminiferi contorti per mm2 by up to 44.8% – a decrease in the percentage of Tubuli seminiferi contorti of the total testes tissue by up to 39.1%     

Scanning electron and light microscopic studies of the surface epithelium of the rete testis and epididymis of the boar. I. Rete testis and efferent ducts

The use of the scanning electron microscope gave a three dimensional representation of the epithelial surface. Additionally, light microscopy revealed the representative structure of the epithelium. The rete testis showed a single layer of cubic epithelial cells. Short and dense microvilli were found on the surface. Sporadically a single, cilia-like structure was recognized. An extratesticular rete testis was identified. The flowing transition of the epithelium between the rete testis and the efferent ductuli occurred at different levels, so that both kinds of epithelial structures were recognized in the same area. The efferent ductuli were composed of a single columnar epithelium consisting of two cell types, principal cells and ciliated cells. The ciliated cells were recognized by their cilia protruding into the lumen. The principal cells showed microvilli on their surface and bleblike apical protrusions which erupt into the lumen.     

Effects of in utero exposure to nonsteroidal estrogens on mouse testis.

Male mice exposed in utero to alpha-zearalanol (zeranol) or diethylstilbestrol (DES) were analyzed postnatally to evaluate the possible changes on their testicular morphology as part of an examination of the effects of transplacental exposure to non-steroidal estrogens on sensitive tissues. Pregnant NMRI mice were injected subcutaneously with ethyl oleate (0.1 mL) alone (negative control) or with 150 micrograms/kg of body weight of zeranol or DES (positive control) on days 9 and 10 of gestation. Experimental and control male offspring were euthanized at days 45 (n = 47), 90 (n = 44), 180 (n = 40) and 365 (n = 26) after birth and their gonads were examined by light and electron microscopy. The results suggested that prenatal zeranol or DES exposure induced more severe and earlier (at 45 d) testicular abnormalities than in negative control (at 6 mo). These age-related alterations were characterized by regressive changes in the germinal epithelium and Sertoli's cells as well as foci of Leydig's cells around atrophied seminiferous tubules and dysplasia of the rete testis epithelium. On the contrary, the presence of Leydig's cells with immature morphology and their arrangement in sheet could be attributable exclusively to estrogen treatment. The presence of no neoplasm was confirmed.     

Zur Entwicklung des Pferdehodens

The aim of the study was to answer the open questions concerning the development of the horse's testis. This study revealed that the seminiferous tubules originate from the sex cords of the coelomic epithelium and Leydig cells from the proximal part of mesonephric nephrones, whereas the rete and the ductuli efferentes derive from intermediate and distal parts of the mesonephric tubules. During the development the Leydig cells undergo an enormous proliferation due to the PMSG secretion in the mare. The proliferation of these cells prevent the deep penetration of the rete into the medulla and is therefore the reason for the reduced extension of the rete and mediastinum testis in the stallion, although 80% of these cells degenerate in the last third of pregnancy. The growth of the seminiferous tubules during sexual maturity reduces the rete to the extremitas capitata of the testis.     

Stereological analysis of Wistar rat testis during early post-natal development

Quantitative analysis of testis structure was performed during early post-natal development in Wistar rats. For this purpose, at 1, 7, 14, 21, 28, 35, 42, 60 and 90 days after birth, weights and volumes of testes were recorded and fixed in Bouin's solution. For stereological studies, 5-μm paraffin sections were stained with haematoxylin-eosin. Relative and then absolute volumes of seminiferous tubules, germinal epithelium, seminiferous tubuli lumina and interstitial tissue were estimated by point-counting method. The results showed that weight and volume of testis in rats increase 75- and 86.28-fold during post-natal development, respectively. The greatest growth rate (2.96-fold) of testis was observed between days 35 and 42. Also, diameter of seminiferous tubules increased significantly (P<0.001) between different ages and represented 5.55-fold increase during post-natal development. The percentage volume of tubular tissue increased 1.4-fold between birth and 90 days of age. Interstitial tissue formed 36.68±0.90% of testicular parenchyma at birth. This percentage decreased progressively during post-natal development until 90 (9.00±0.55%) days of age. Lumen of seminiferous tubules was recognized at day 28, and its relative volume increased with age. This study provides systematic data on the stereological characteristics of developing Wistar rat testis.     

"Nuage" in the Primordial Germ Cells of the Chick Embryo

The primordial germ cells (PGC) of the chick embryo in stage 4 of Hamburger /Hamilton (1951) have cytoplasmic formations similar in shape, texture, aggregation and relations with other cell components to the germinal plasm and “nuage” described in other species. The observation of this material in the earliest period of differentiation of PGC suggest that this substance plays an essential role in the determination of the germinal line in birds. The observation of “nuage” material in the PGC of the chick embryo adds evidence for this formation in germ cells.     

Prenatal development of the horse ovary]

To answer the many open questions concerning the development of the horse's ovary, first the prenatal development was investigated. It resulted that follicles derive from the germinal epithelium and its cords, whereas the Leydig cells and the rete blastema originate from the mesonephros. In the second third of pregnancy the Leydig cells undergo an enormous proliferation, in the last third they degenerate. However this degeneration is not connected with the postnatal development of the ovulation groove.     

Ultrastructure of the Rete testis in the Cat (Felis domestica,L.)*

The rete testis (RT) in the cat comprises three distinct and sequential parts: septal or adlobular; mediastinal and tunical parts. This last part is followed by the small extratesticular rete testis. The whole of the RT tubules and/or channels is lined by single low columnar and/or cuboidal epithelium with ultrastructural peculiarities of secretory and absorptive functions. The Golgi apparatus polarity (cis-trans surfaces), its relation with the long profiles of the ER, mainly with the rough ER, and presence of apical uncoated electrondense granules are suggestive of active release of macromolecules, probably glycoproteins. The absorptive function is proposed through the observation of a conspicuous microvacuolar-vesicular apical complex in epithelial cells. Moreover spermatozoa phagocytosis is also noticed, mainly in the septal part of the RT.     

Scanning electron microscopy of circulating primordial germ cells in the chick embryo

A demonstration of circulating primordial germ cells in the stage 14 embryo was carried out. The definition of primordial cells was based upon specific criteria utilized by other workers and developed in this study. Evidence supports a passive transport of these cells to the germinal epithelium.     

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.     

Histopathological effects of boldenone in cattle

Histopathology of male cattle previously found positive for béta-boldenone in urine in the Netherlands and in Italy was studied. The animals were derived from practice and several weeks had passed after the finding of béta-boldenone before the animals were examined. The animals consisted of 34 male veal calves and one finishing bull. In the prostate gland hypersecretion, cyst formation (45%) and hyperplasia of the urethral epithelium was observed, in the bulbo-urethral gland similar alterations were present. The testis showed reduced development and degeneration of the germinal epithelium (70%), leading to debris and syncytial cell formation in the lumina. Stromal proliferation was evident. In some animals the liver was sampled and showed periportal fibrosis, bile duct proliferation and sometimes necrosis. The bull also showed degeneration of the germinal epithelium of the testis and absence of sperm production, the prostate gland showed some secretion and had an atrophic appearance. It is concluded that béta-boldenone may lead to degeneration of the germinal epithelium of the testis and hypersecretion and cyst formation in the prostate and bulbo-urethral gland, which alterations may heal in time.     

Bilateral cystic rete testis in an alpaca (Lama pacos).

A 9-year-old intact male alpaca (Lama pacos) was examined because of marked enlargement of the left scrotum. Ultrasound examination revealed a thin-walled anechoic structure in the area of the left testis. Aspirated fluid contained spermatozoa, many of which had abnormal morphology. Castration was performed and the left testis was markedly enlarged with a clear fluid-filled cyst. The cyst was lined by a single layer of squamous to cuboidal epithelial cells consistent with those originating from rete testis. The right testis was of a comparable size and shape to that of normal alpaca testis, but the rete testis was mildly to moderately dilated. Additional findings included chronic inflammation of the right testis and epididymis and epididymal fibrosis with ductal hyperplasia on the left. The diagnosis was bilateral cystic rete testis, most likely secondary to chronic inflammation.     

Immunohistochemical demonstration of myoid cells in the testis and its excurrent ducts in the domestic fowl

(1) Immunohistochemical methods and three antibodies (against actin, desmin and smooth muscle actin) were used to demonstrate the myoid cells in the domestic fowl testis and its excurrent ducts. (2) A positive reaction to actin, smooth muscle actin and desmin was found in the myoid cells of peritubular tissue of the testis and in rete testis, ductuli efferentes and ductus epididymidis. (3) In the testis myoid-reactive cells form a single layer. In the rete testis, ductuli efferentes and the ductus epididymidis reactive myoid cells form a main component of the stroma. (4) Positive reaction to actin, smooth muscle actin and desmin was also observed in the myoid cells of the tunica albuginea and in the wall of blood vessels in the testis and epididymis, indicating a contractile function for the testicular capsule.     

Production of germ-line chimeras by the transfer of cryopreserved gonadal germ cells collected from 7- and 9-day-old chick embryos

Gonadal germ cells (GGC) were collected from the gonads of 7‐ or 9‐day‐old White Leghorn chick embryos and suspended in freezing medium containing 10% dimethylsulfoxide (DMSO). The cell suspension was frozen at ?1°C/min. until the temperature reached ?80°C. Then, the cells were immersed in liquid nitrogen at ?196°C and stored for 3–4 months. Approximately 50 frozen/thawed GGC were injected into the dorsal aorta of each 2‐day‐old Rhode Island Red (RIR) embryo, from which blood was drawn before germ‐cell injection. The injected embryos were incubated until they hatched and the chicks were raised until sexually mature. On reaching sexual maturity, a progeny test was performed by mating recipient chicks with normal RIR of the opposite sex. Progenies were obtained from male germ cell recipients that were injected with germ cells collected from 7‐ and 9‐day‐old embryos. The results demonstrated that frozen/thawed GGC collected from 7‐ or 9‐day‐old fertilized eggs can be used to produce male germ‐line chimeras.     

Full-term development of offspring using round spermatids produced ectopically from fetal male germ cells

The continuous production of mammalian sperm is maintained by the proliferation and differentiation of spermatogonial stem cells, which originate from primordial germ cells in the early embryo. Previously, we reported that the transplantation of fetal male gonadal tissue into the recipient testis was effective obtaining functional sperm. This transplantation technique is a promising new approach for the preservation of testicular function in a mutant animal with embryonic lethality. In the present study, we examined whether spermatogenesis from fetal male germ cells is induced under ectopic conditions in male and female recipients. Nine to 10 weeks after the transplantation of male gonads prepared from embryos at 12.5 or 16.5 days post gestation, male germ cell differentiation occurred under the skin of male and female recipient nude mice. Histological analyses revealed that grafted gonads contained haploid germ cells such as round or elongated spermatids. Furthermore, we succeeded in obtaining normal progeny by injecting the ectopically produced round spermatids into the cytoplasm of oocytes, even when the male germ cells had been generated in female recipients. These results indicate that the transplantation of fetal male gonads under the skin of recipient mice is a useful technique for obtaining functional male gametes.     

Immunolocalisation of oestrogen receptors alpha (ERalpha) and beta (ERbeta) in porcine embryos and fetuses at different stages of gestation

The sites of oestrogen action can be shown by the localisation of their receptors in the target tissues. The aim of the present study was to show the localisation of oestrogen receptors in porcine embryos and fetuses obtained on days 18, 22, 32, 40, 50, 60, 71 and 90 post coitum (p.c.). The visualisation of proteins was conducted in embryos and various fetal organs such as gonads, uterus, lung, kidney, intestine and adrenal gland. Both ERs were observed in the blastocysts on day 18 p.c. In the male, ERbeta was detected in the testis and epididymis, whereas ERalpha was present in the efferent ductules. In the female, ERbeta was detected in the ovarian stromal cells investing the oocyte nests, while ERalpha protein was detected in the surface epithelium. In the uterus, ERs were present in the stromal cells, while ERbeta was present in the luminal epithelium. In the non-reproductive fetal porcine tissues ERbeta was localised in the lungs, kidneys, adrenal glands and in the umbilical cords. Both ERs were observed in the intestine. It is possible that ERbeta may play important roles in the development of the adrenal gland, testis, kidney and lungs, while both ERs are involved in the development of the ovary, uterus, epididymis and intestine of the porcine fetus.     

Surgical technique to cannulate the rete testis of the goat

A surgical technique was devised to collect rete testis fluid from 14 mature goats. The tubular portion of the extratesticular rete testis was cannulated where it penetrated the tunica albuginea of the testis under the center of the head of the epididymis. The tip of the cannula was sutured in place in the extratesticular rete testis and the opposite end was passed through the scrotum and into a plastic collection bottle. The bottle was glued to pillow ticking, which was sutured to the scrotum. Continuous flow of rete testis fluid occurred for 0 to 14 days and was usually terminated by a sperm clot in the cannula. The flow rate was 0.59 +/- 0.37 ml/hr.     

Immunohistochemical Localization of Progesterone Receptor Isoforms in the Chick Pre-follicular Ovary

The distribution of progesterone receptor A and B isoforms in different cell types of the chick pre-follicular ovary was studied by immunohistochemistry. Newly hatched chicks were killed and the left ovary was removed, fixed and embedded in paraplast. Sections (5 microns thick) were made for the detection of progesterone receptor isoforms, using a technique of indirect immunoperoxidase. The results indicate that progesterone receptors were localized in the nuclei of germinal epithelium and germ cells of the ovarian cortex and in the interstitial and epithelial cells of the lacunar channels of the ovarian medulla. Undifferentiated cells did not present progesterone receptors. In all cell subpopulations progesterone receptor B was the predominantly expressed isoform. These data suggest that progesterone receptor isoforms are differentially expressed in the chick pre-follicular ovary and that progesterone effects in this tissue are mediated by the progesterone receptor B isoform.