The Sertoli cell of the water buffalo (Bubalus bubalis) during the spermatogenic cycle

Summary Ultrastructural features and morphometric evaluations of buffalo Sertoli cells are reported for the six phases of the spermatogenic cycle. The phases of the tubular seminiferous epithelium are identified according to characteristic cellular associations with completed spermiation as demarcation between two cycles. Average tubular diameter (245 m) and epithelial height (61 m) do not vary significantly during the cycle. The relative Sertoli cell volume in the seminiferous epithelium varies between 30% (phase 4) and 39% (phase 8). The calculated volume of a single Sertoli cell increases from a nadir of 7118 m³ in phase 3 abruptly to a maximum of 8968 m³ in phase 4 and is then gradually reduced during the following phases. The Sertoli cell surface area shows a similar trend: it amounts to 11105 m² in phase 3 and to 14260 m² in phase 4. The contact area of the Sertoli cell with adjacent cells and structures is subject to characteristic changes; from the expansion of basal Sertoli-Sertoli contacts it is concluded that the blood-testis barrier in the buffalo is particularly tight during phases 8, 1 and 2. The irregularly contoured nucleus contains a vesicular nucleolus, has a calculated volume from 465 m³ to 543 m³ and occupies 5 to 7% of the cell. Volume percentages of mitochondria (4%), Golgi apparatus and lysosomal bodies are rather constant during the cycle. Whorls and orderly arranged aggregates of the smooth endoplasmic reticulum occur in basal location as well as in close association with elongating spermatids. Smooth ER is the organelle that exhibits the most prominent changes during the Sertoli cell cycle: it occupies 5.79% in phase 3 and 20.9% in phase 4 of the total cellular volume. Phagocytosis of residual bodies is insignificant in this species and a lipid cycle is absent in buffalo Sertoli cells.     

Observations on the inter-relationships of Sertoli cells at the level of the blood- testis barrier: evidence for formation and resorption of Sertoli-Sertoli tubulobulbar complexes during the spermatogenic cycle of the rat.

Structures termed tubulobulbar complexes are known to be formed by adjoining Sertoli cells at the level of the blood-testis barrier (Russell and Clermont, '76). Here, long (2-4 micrometer) tubular evaginations of one Sertoli cell, which end in bulbous dilations, are seen in corresponding invaginations of a neighboring Sertoli cell. In most regions of the tubular and bulbous portions of the complex, the Sertoli plasma membranes were found to be separated by a 4-5-nm intercellular space, but in some areas the membranes converged to form tight and gap junctions. The numbers, distribution and properties of tubulobulbar complexes were studied in relation to the cycle of the seminiferous epithelium. From the data obtained it was concluded that tubulobulbar complexes develop and undergo regressive changes during the spermatogenic cycle. Most complexes arise during the early stages of the cycle (Stages II-V) and develop large bulbous endings. Developing tubulobulbar complexes consist of short evaginations of one Sertoli cell which face a bristle-coated pit of the opposing Sertoli cell. At midcycle (Stages VI-VII) most show regressive changes and are eventually resorbed as a consequence of the action of nearby Sertoli lysosomes. Once resorbed, the probability of seeing a tubulobulbar complex in thin sections decreases from 4- to 8-fold. The few tubulobulbar complexes which remain past this period (Stages VII-XIV-I) usually lack bulbous endings and are fequently seen above type A spermatogonia. The data suggest that small fragments of cytoplasm and plasma membrane (including junctional surfaces) are lost from one Sertoli cell as a result of the degradative processes occurring in a neighboring Sertoli cell. Tubulobulbar resorption is discussed in relation to the impending breakdown of the blood-testis barrier above spermatocytes as these cells move upward. The possible significance of the cyclic resorption of tight and gap junctional sites between Sertoli cells is also discussed.     

Spermiation in the Mouse: Contribution of the Invading Sertoli Cell Process to Adluminal Displacement of the Spermatid Head

At the maturation phase of spermiogenesis in mice, the spermatid heads that are embedded deeply in the epithelium of the seminiferous tubules dislocate toward the luminal surface. In the present study, to clarify the manner in which the spermatid head is displaced toward the lumen, morphological changes in spermatids and Sertoli cells were examined on ultrathin and thick sections stained with adenosine triphosphatase cytochemistry. During adluminal displacement, the spermatid head is surrounded by an invading process of Sertoli cell which invaginates into the spermatid cytoplasm to form complicated passages called the canal complex. At the site of the spermatid head, the wall of an invading Sertoli cell process folds to form a sheath in which the spermatid head is located. The sheath correspond to a structure known as ectoplasmic specialization. The invading Sertoli cell process also shows branching and swelling at the site where spermatid heads are present. The present results suggest that the canal complex is directly involved in the adluminal displacement of the spermatid head. Dynamic changes of invading Sertoli cell processes may produce the motive force for adluminal displacment of the spermatid head. Also, ectoplasmic specialization may contribute to the adluminal displacement of the spermatid possibly by mediating cell to cell interaction between the spermatid nucleus and the invading Sertoli cell process.     

Spermiogenesis in the bullfrog (Rana catesbeiana): a study of cytoplasmic events including cell volume changes and cytoplasmic elimination

The process by which spermatid cytoplasmic volume is reduced and cytoplasm eliminated during spermiogenesis was investigated in the bullfrog Rana catesbeiana. At early phases of spermiogenesis, newly formed, rounded spermatids were found within spermatocysts. As acrosomal development, nuclear elongation, and chromatin condensation occurred, spermatid nuclei became eccentric within the cell. A cytoplasmic lobe formed from the caudal spermatid head and flagellum and extended toward the seminiferous tubule lumen. The cytoplasmic lobe underwent progressive condensation whereby most of its cytoplasm became extremely electron dense and contrasted sharply with numerous electron-translucent vesicles contained therein. At the completion of spermiogenesis, many spermatids with their highly condensed cytoplasm still attached were released from their Sertoli cell into the lumen of the seminiferous tubule. There was no evidence of the phagocytosis of residual bodies by Sertoli cells. Because spermatozoa are normally retained in the testis in winter and are not released until the following breeding season, sperm were induced to traverse the duct system with a single injection of hCG. Some spermatids remained attached to their cytoplasm during the sojourn through the testicular and kidney ducts; however, by the time the sperm reached the Wolffian duct, separation had occurred. The discarded cytoplasmic lobe (residual body) appeared to be degraded with the epithelium of the Wolffian duct. It was determined that the volume of the spermatid was reduced by 87% during spermiogenesis through a nuclear volume decrease of 76% and cytoplasmic volume decrease of 95.3%.     

Morphometric studies on lipid inclusions in Sertoli cells during the spermatogenic cycle in the rat

Summary The volume and surface area of lipid inclusions often present in the cytoplasm of rat Sertoli cells was measured directly from semi-thin sections of perfusion-fixed testicular tissues using an image analyser linked to a light microscope. Sertoli cell nuclei were used as a reference for comparing any variations in the measured parameters of lipid inclusions during the rat spermatogenic cycle. Volume density of Sertoli cell lipid inclusions was assessed by morphometric analysis of Sertoli cells photographically reconstructed from electron micrographs. Maximum lipid content in Sertoli cells occurred during stages IX–XIV of the spermatogenic cycle, then declined at stages I–III and remained low from stages IV–VIII. The persistence and increase in number of many large Sertoli cell lipid inclusions beyond the stage where spermatid residual bodies are phagocytosed within the Sertoli cells (stage IX) suggests that the synthesis and lipolysis of Sertoli cell lipid inclusions represents an intrinsic functional cycle of the Sertoli cells. Stage-dependent variations in the lipid content of rat Sertoli cells offers morphological evidence that the metabolic duties of the Sertoli cells are synchronised with the spermatogenic cycle to provide local coordination of the proliferation and maturation of the germ cells.     

Sertoli cell ectoplasmic specializations in the seminiferous epithelium of the testosterone-suppressed adult rat

The Sertoli cell ectoplasmic specialization is a unique junctional structure involved in the interaction between elongating spermatids and Sertoli cells. We have previously shown that suppression of testicular testosterone in adult rats by low-dose testosterone and estradiol (TE) treatment causes the premature detachment of step 8 round spermatids from the Sertoli cell. Because these detaching round spermatids would normally associate with the Sertoli cell via the ectoplasmic specialization, we hypothesized that ectoplasmic specializations would be absent in the seminiferous epithelium of TE-treated rats, and the lack of this junction would cause round spermatids to detach. In this study, we investigated Sertoli cell ectoplasmic specializations in normal and TE-treated rat testis using electron microscopy and localization of known ectoplasmic specialization-associated proteins (espin, actin, and vinculin) by immunocytochemistry and confocal microscopy. In TE-treated rats where round spermatid detachment was occurring, ectoplasmic specializations of normal morphology were observed opposite the remaining step 8 spermatids in the epithelium and, importantly, in the adluminal Sertoli cell cytoplasm during and after round spermatid detachment. When higher doses of testosterone were administered to promote the reattachment of all step 8 round spermatids, newly elongating spermatids associated with ectoplasmic specialization proteins within 2 days. We concluded that the Sertoli cell ectoplasmic specialization structure is qualitatively normal in TE-treated rats, and thus the absence of this structure is unlikely to be the cause of round spermatid detachment. We suggest that defects in adhesion molecules between round spermatids and Sertoli cells are likely to be involved in the testosterone-dependent detachment of round spermatids from the seminiferous epithelium.     

An ultrastructural and autoradiographic study of the immune response in Hyalophora cecropia pupae

Summary Membrane-bounded spherical vesicles found in rat Sertoli cells have been examined quantitatively during the cycle of the seminiferous epithelium. Most of the vesicles were localized to the basal and columnar portions of the Sertoli cell cytoplasm. The thin lateral projections of the Sertoli cells contained very few vesicles. Morphometric analysis of the basal portion of the Sertoli cell cytoplasm revealed that the volume density (V _v ) of the vesicles changed markedly during the cycle. The V _v was at its minimum (0.036) at stage VII and maximum (0.117) at stages XI-I. The vesicles were also smaller at stage VII compared to the vesicles at stages IX-V. The stage-dependent difference in the size of the vesicles was found both in the basal and the columnar portions of the Sertoli cells. At stage VII some of the vesicles appeared to be elongated much like the tubular elements of the smooth endoplasmic reticulum (SER) from which they are probably derived. The stage-dependent differences in volume density and size of the Sertoli cell vesicles may be related to cyclic biochemical variations in the Sertoli cells, and are further indications of a variation in Sertoli cell function during the cycle of the seminiferous epithelium. Whether or not this is due to an internal cycle of the Sertoli cell or to influences from adjacent germ cells remains to be determined.     

The numbers of Sertoli cells in mature Holstein bulls and their relationship to quantitative aspects of spermatogenesis

Testes from 37 Holstein bulls, 38-99 mo of age, were used to investigate the relationship of Sertoli cell number, Sertoli cell-germ cell ratios and other related factors to daily sperm production (DSP). DSP was assessed by enumeration of spermatids in testicular homogenates, whereas Sertoli cell and germ cell ratios were based on direct counts in 20 round Stage VIII seminiferous tubular cross sections per bull. Numbers of Sertoli cells were calculated as (total homogenization resistant spermatids:spermatid:Sertoli cell ratio)/0.394; the factor of 0.394 adjusted for the presence of homogenization resistant spermatids during only 39.4% of the spermatogenic cycle. Data were subjected to simple linear and second-order regression analyses. Positive linear relationships were observed between DSP and testicular parenchymal weight (p less than 0.005, R = +0.71), DSP per gram (p less than 0.005, R = +0.79), total Sertoli cells (p less than 0.005, R = +0.83), Sertoli cells per gram (p less than 0.01, R = +0.47) and the yield of Step 8 spermatids per Type A spermatogonium (p less than 0.05, R = +0.34). DSP was not related (p greater than 0.10) to the number of germ cells supported per Sertoli cell. Testicular parenchymal weight and DSP per gram were unrelated to each other (p greater than 0.10), but both were related (p less than 0.005) to the total Sertoli cell number (R = +0.61 and +0.62, respectively). Total number of Sertoli cells accounted for more of the variation in DSP between bulls (R2 = 68.2%) than did any other factor examined. It was suggested that total Sertoli cell number may be an important determinant of a bull's spermatogenic potential.     

Rai14 (Retinoic Acid Induced Protein 14) Is Involved in Regulating F-Actin Dynamics at the Ectoplasmic Specialization in the Rat Testis*

Rai14 (retinoic acid induced protein 14) is an actin binding protein first identified in the liver, highly expressed in the placenta, the testis, and the eye. In the course of studying actin binding proteins that regulate the organization of actin filament bundles in the ectoplasmic specialization (ES), a testis-specific actin-rich adherens junction (AJ) type, Rai14 was shown to be one of the regulatory proteins at the ES. In the rat testis, Rai14 was found to be expressed by Sertoli and germ cells, structurally associated with actin and an actin cross-linking protein palladin. Its expression was the highest at the ES in the seminiferous epithelium of adult rat testes, most notably at the apical ES at the Sertoli-spermatid interface, and expressed stage-specifically during the epithelial cycle in stage VII-VIII tubules. However, Rai14 was also found at the basal ES near the basement membrane, associated with the blood-testis barrier (BTB) in stage VIII-IX tubules. A knockdown of Rai14 in Sertoli cells cultured in vitro by RNAi was found to perturb the Sertoli cell tight junction-permeability function in vitro, mediated by a disruption of F-actin, which in turn led to protein mis-localization at the Sertoli cell BTB. When Rai14 in the testis in vivo was knockdown by RNAi, defects in spermatid polarity and adhesion, as well as spermatid transport were noted mediated via changes in F-actin organization and mis-localization of proteins at the apical ES. In short, Rai14 is involved in the re-organization of actin filaments in Sertoli cells during the epithelial cycle, participating in conferring spermatid polarity and cell adhesion in the testis.     

Relative volume of Sertoli cells in monkey seminiferous epithelium: a stereological analysis.

Techniques of quantitative stereology have been utilized to determine the relative volume occupied by the Sertoli cells and germ cells in two particular stages (I and VII) of the cycle of the seminiferous epithelium. Sertoli cell volume ranged from 24% in stage I of the cycle to 32% in stage VII. Early germ cells occupied 3.4% in stage I (spermatogonia) and 8.7% in stage VII (spermatogonia and preleptotene spermatocytes). Pachytene spermatocytes occupied 15% (Stage I) and 24% (stage VII) of the total volume of the seminiferous epithelium. In stage I the two generations of spermatids comprised 58% of the total epithelium by volume, whereas in stage VII, after spermiation, the acrosome phase spermatids occupied 35% of the total seminiferous epithelial volume.     

Morphometric studies on hamster testes in gonadally active and inactive states: light microscope findings

This study provides quantitative information on the testes of seasonally breeding golden hamsters during active and regressed states of gonadal activity. Seminiferous tubules occupied 92.5% of testis volume in adult gonadally active animals. Leydig cells constituted 1.4% of the testicular volume. The mean volume of an individual Leydig cell was 1092 microns 3, and each testis contained about 25.4 million Leydig cells. The volume of an average Sertoli cell nucleus during stage VII-VIII of the cycle was 502 microns 3. A gram of hamster testis during the active state of gonadal activity contained 44.5 million Sertoli cells, and the entire testis contained approximately 73.8 million Sertoli cells. Testes of the hamsters exposed to short photoperiods for 12-13 wk displayed a 90% reduction in testis volume that was associated with a decrease in the volume of seminiferous tubules (90.8% reduction), tubular lumena (98.8%), interstitium (72.7%), Leydig cell compartment (79.3%), individual Leydig cells (69.7%), Leydig cell nuclei (50.0%), blood vessels (85.5%), macrophages (68.9%), and Sertoli cell nuclei (34.1%). The diameter (61.1%) and the length (36.8%) of the seminiferous tubules were also decreased. Although the number of Leydig cells per testis was significantly lower (p less than 0.02) after short-photoperiod exposure, the number of Sertoli cells per testis remained unchanged. The individual Sertoli cell in gonadally active hamsters accommodated, on the average, 2.27 pre-leptotene spermatocytes, 2.46 pachytene spermatocytes, and 8.17 round spermatids; the corresponding numbers in the regressed testes were 0.96, 0.20, and 0.04, respectively. The striking differences in the testicular structure between the active and regressed states of gonadal activity follow photoperiod-induced changes in endocrine function and suggest that the golden hamster may be used as a model to study structure-function relationships in the testis.     

Testis morphometry,seminiferous epithelium cycle length,and daily sperm production in domestic cats (Felis catus)

There is very little information regarding the testis structure and function in domestic cats, mainly data related to the cycle of seminiferous epithelium and sperm production. The testis weight in cats investigated in the present study was 1.2 g. Compared with most mammalian species investigated, the value of 0.08% found for testes mass related to the body mass (gonadosomatic index) in cats is very low. The tunica albuginea volume density (%) in these animals was relatively high and comprised about 19% of the testis. Seminiferous tubule and Leydig cell volume density (%) in cats were approximately 90% and 6%, respectively. The mean tubular diameter was 220 microm, and 23 m of seminiferous tubule were found per testis and per gram of testis. The frequencies of the eight stages of the cycle, characterized according to the tubular morphology system, were as follows: stage 1, 24.9%; stage 2, 12.9%; stage 3, 7.7%; stage 4, 17.6%; stage 5, 7.2%; stage 6, 11.9%; stage 7, 6.8%; and stage 8, 11 %. The premeiotic and postmeiotic stage frequency was 46% and 37%, respectively. The duration of each cycle of seminiferous epithelium was 10.4 days and the total duration of spermatogenesis based on 4.5 cycles was 46.8 days. The number of round spermatids for each pachytene primary spermatocytes (meiotic index) was 2.8, meaning that significant cell loss (30%) occurred during the two meiotic divisions. The total number of germ cells and the number of round spermatids per each Sertoli cell nucleolus at stage 1 of the cycle were 9.8 and 5.1, respectively. The Leydig cell volume was approximately 2000 microm3 and the nucleus volume 260 microm3. Both Leydig and Sertoli cell numbers per gram of testis in cats were approximately 30 million. The daily sperm production per gram of testis in cats (efficiency of spermatogenesis) was approximately 16 million. To our knowledge, this is the first investigation to perform a more detailed and comprehensive study of the testis structure and function in domestic cats. Also, this is the first report in the literature showing Sertoli and Leydig cell number per gram of testis and the daily sperm production in any kind of feline species. In this regard, besides providing a background for comparative studies with other fields, the data obtained in the present work might be useful in future studies in which the domestic cat could be utilized as an appropriate receptor model for preservation of genetic stock from rare or endangered wild felines using the germ cell transplantation technique.     

细胞松弛素E对大鼠生精细胞发育的影响

本文采用微丝抑制剂——细胞松弛素E对大鼠生精细胞发育的影响作了形态学观察,特别对支持细胞骨架复合体的作用进行了较为详细的研究。结果表明睾丸内注射0.1ml,1000μmol/L～2000μmol/L,细胞松弛素E,6-14小时后,光镜下可见曲细精管上皮排列疏松,组合紊乱,有的生精上皮基底部出现双核和三核的圆形细胞和多核巨精子细胞,管腔内出现未成熟的精子;在第ⅤⅢ～Ⅸ期曲细精管上皮中,有许多第8、第9期的精子细胞顶体不指向基底方向,属定向不正的精子。电镜下,实验组动物可见一些面向第8-18期精子细胞顶体的支持细胞骨架复合体出现不同程度的缺如,有的断裂成小段;有的破坏仅发生在顶体上方;有的几乎全部丢失,并有类管球复合体的形成。另外,在高渗液处理下,可见精子细胞顶体和支持细胞间的间隙扩大。最后对微丝在精子发育中的作用进行了讨论。     

Evidence that tubulobulbar complexes in the seminiferous epithelium are involved with internalization of adhesion junctions

Tubulobulbar complexes may be part of the mechanism by which intercellular adhesion junctions are internalized by Sertoli cells during sperm release. These complexes develop in regions where Sertoli cells are attached to adjacent cells by intercellular adhesion junctions termed ectoplasmic specializations. At sites where Sertoli cells are attached to spermatid heads, tubulobulbar complexes consist of fingerlike processes of the spermatid plasma membrane, corresponding invaginations of the Sertoli cell plasma membrane, and a surrounding cuff of modified Sertoli cell cytoplasm. At the terminal ends of the complexes occur clusters of vesicles. Here we show that tubulobulbar complexes develop in regions previously occupied by ectoplasmic specializations and that the structures share similar molecular components. In addition, the adhesion molecules nectin 2 and nectin 3, found in the Sertoli cell and spermatid plasma membranes, respectively, are concentrated at the distal ends of tubulobulbar complexes. We also demonstrate that double membrane bounded vesicles are associated with the ends of tubulobulbar complexes and nectin 3 is present on spermatids, but is absent from spermatozoa released from the epithelium. These results are consistent with the conclusion that Sertoli cell and spermatid membrane adhesion domains are internalized together by tubulobulbar complexes. PKCalpha, a kinase associated with endocytosis of adhesion domains in other systems, is concentrated at tubulobulbar complexes, and antibodies to endosomal and lysosomal (LAMP1, SGP1) markers label the cluster of vesicles associated with the ends of tubulobulbar complexes. Our results are consistent with the conclusion that tubulobulbar complexes are involved with the disassembly of ectoplasmic specializations and with the internalization of intercellular membrane adhesion domains during sperm release.     

Development of the acrosome and alignment,elongation and entrenchment of spermatids in procarbazine-treated rats

Intraperitoneally administered procarbazine caused, among other features previously reported (Russell et al., 1983), specific defects in the acrosome of cap phase spermatids of the rat seminiferous epithelium. The effect of procarbazine was to fragment and eventually cause resorption of the acrosomes of a small number of steps 5–9 spermatids. Although the acrosome was lost, dose union of the leaflets of the nuclear envelope underlying the acrosomal sac was maintained as was the marginal fossa and acrosomal zonule. Spermatids at steps 8 and 9 of development, which had lost their acrosomes, showed nuclei which were eccentric within the cell—a feature which normally occurs at these steps of spermiogenesis in acrosome intact cells. Even without an acrosomal sac, the plasma membrane of these cells (in stage VIII) became orientated to the region of the nuclear membrane which would have underlaid the acrosome. Although abundant, Sertoli ectoplasmic specialization did not become aligned with the spermatid head. The spermatid failed to become orientated within the seminiferous epithelium and failed to enter the crypts within the Sertoli cell as usually occurs during the elongation process. Thus, the presence of an acrosome is not likely related to the formation of an eccentric nucleus or the alignment of the surface of the nucleus which would normally underlay the acrosome with the cell's plasma membrane (internal alignment). The presence of an acrosome may be related to the alignment of the spermatid head with the ectoplasmic specialization, which in turn may influence the orientation and positioning of the late spermatids within the seminiferous epithelium (external alignment) and their position within recesses of the Sertoli cell. This study also suggests a role for the manchette in the process of elongation of the spermatid.     

A scanning electron microscopic study of germ cell maturation in the reproductive tract of the male soupfin shark (Galeorhinus galeus)

Germ cell maturation in the reproductive tract of the soupfin shark (Galeorhinus galeus) was studied using scanning electron microscopy (SEM). The SEM showed changes in Sertoli cytoplasm volume during spermatogenic development. In immature spermatocysts in the germinal zone, spermatogonia were embedded in Sertoli cytoplasm. In spermatogonial spermatocysts, Sertoli cells were adluminally located in the spermatocyst, with spermatogonia enveloped in the basal portions of the cytoplasm. During the round spermatid stage, Sertoli cytoplasm was very scanty. Spermatid elongation was accompanied by a progressive increase in the volume of Sertoli cytoplasm, notably around the spermatid heads. In the mature spermatocyst, bundles of spermatozoa are totally enveloped by Sertoli cytoplasm. Spermatozoa occurred randomly in the epididymis. However, in the ampulla ductus deferentis, spermatozoa reaggregated and were embedded in a mucoid substance to form highly ordered spherical bundles. In the sperm bundle, the spermatozoa heads were arranged such that the helical turns of adjacent spermatozoa were precisely aligned, and all the heads in the bundle formed a distinct apex. This study demonstrates the utility of exploring the relationship between germ cells and Sertoli cells in an evolutionarily ancient vertebrate, such as the shark.     

The role of sertoli cells in spermatid maturation in the testis of the crayfish, Procambarus paeninsulanus

With the onset of spermiogenesis, many changes become apparent in the crayfish spermatid during its transition to mature sperm. The nucleus passes through a series of stages, excess cytoplasm is removed, the acrosome develops, and nuclear arms form and become wrapped around the sperm prior to its enclosure in a capsule. Changes are also apparent in the Sertoli cells surrounding the germ cells in the crayfish testis. The amount of cytoplasm of individual Sertoli cells appears to increase in quantity and changes in the intracellular organelles become apparent. As spermiogenesis commences, the cytoplasm along one side of Sertoli cells adjacent to the spermatids is devoid of obvious organelles. Numerous finger/like projections of Sertoli cytoplasm penetrate into the spermatid and appear to isolate portions of the sperm cytoplasm. During later stages of spermiogenesis, several vesicles in the Sertoli cells which appear to contain droplets of this isolated sperm cytoplasm. appear to undergo lytic changes, As the amount of cytoplasm of the spermatid is reduced, contact is maintained between the spermatid and Sertoli cell in the area of the acrosome. The nuclear arms of the sperm extend into the Sertoli cell during their formation and later become wrapped around the acrosomal area of the sperm. At this time, very little space exists between the Sertoli cell and its many sperm. Large vesicles of electron dense material appear to be released by the Sertoli cells into the space between the sperm and Sertoli cell. This material completely surrounds the sperm and forms the sperm capsule. Spermiation involves the gradual dissolution of the points of contact between the sperm capsule and the Sertoli cell.     

Localization of estrogen receptor α and progesterone receptor B in bovine cervix and vagina during the follicular and luteal phases of the sexual cycle

Abstract

The localization and distribution of estrogen receptors (ERα) and progesterone receptors (PR-B) in the cervix and vagina of sexually mature bovines during the follicular and luteal phases of the sexual cycle were studied using immunohistocehmistry. The estrous cycle stage of 23 Holstein bovines was assessed by gross and histological appearance of ovaries and blood steroid hormone values. Tissue samples from cervix and vagina were fixed in 10% formaldehyde for routine histological processing. Nuclear staining for ERα and PR-B was observed in the epithelial cells of the surface epithelium, stromal cells and smooth muscle cells. Generally, in the cervix, ERα immunoreactivity was more intense in the epithelial and smooth muscle cells during the follicular phase and in the epithelial cells during the luteal phase (p < 0.05). PR-B immunoreactivity was more intense in the epithelial and smooth muscle cells than in the superficial and deep stromal cells during the follicular and luteal phases (p < 0.05). In the vagina, ERα and PR-B immunoreactivities were more intense in the epithelial cells than in the connective tissue cells and smooth muscle cells during the follicular and luteal phases (p < 0.05). These results indicated that the frequency and intensity of ERα and PR-B immunoreactivity in the cervix and vagina of bovines varied according to the cervical and vaginal cell types and the phases of the sexual cycle.     

Role of sulfated glycoprotein-1 (SGP-1) in the disposal of residual bodies by sertoli cells of the rat

Sulfated glycoprotein-1 (SGP-1) is a polypeptide secreted by Sertoli cells in the rat. Sequence analysis revealed a 76% sequence similarity with human prosaposin produced by various cell types. Human prosaposin is a 70 kDa protein which is cleaved in the lysosomes into four 10–15 kDa polypeptides termed saposins A, B, C, and D. The function of lysosomal saposins is to either solubilize certain membrane glycolipids or to form complexes with lysosomal enzymes and/or their glycolipid substrate to facilitate their hydrolysis. The present investigation dealt with the delivery of SGP-1 into the phagosomes of Sertoli cells; these phagosomes contain the residual bodies which detach from the late spermatids at the time of spermiation. Immunogold labeling with anti-SGP-1 antibody was found over Sertoli cell lysosomes, but was absent from phagosomes formed after phagocytosis of spermatid residual bodies in the apical Sertoli cell cytoplasm in stages VIII and early IX of the cycle of the seminiferous epithelium. The phagosomes found later in the basal Sertoli cell cytoplasm in stages IX and X of the cycle became labeled with the antibody as the components of the residual bodies rapidly underwent lysis and disappeared from the Sertoli cells. Sertoli cell lysosomes isolated by cell fractionation (estimated purity of 80%) were found to contain a 65 kDa form of SGP-1 or prosaposin, as well as the 15 kDa polypeptides or saposins. Thus, it appears that this unique lysosomal form of SGP-1 reached the Sertoli cell phagosomes and that their derived polypeptides, the saposins, must play a role in the hydrolysis of membrane glycolipids found in phagocytosed residual bodies. © 1995 Wiley-Liss, Inc.