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C J Gravis

Publications and source records attributed to C J Gravis.

10 recordsLinked to original sources
PubMed1980

Ultrastructural observations on spermatozoa retained within the seminiferous epithelium after treatment with dibutyryl cyclic AMP.

Spermiation was inhibited in the Syrian hamster by administering large doses of dibutyryl cyclic AMP. After treatment with dibutyryl cyclic AMP most stage VIII, IX, and X seminiferous tubules contained some mature spermatozoa within the seminiferous epithelium. The acrosomal membranes and plasma membranes of the unreleased spermatozoa remained intact, indicating that the spermatozoa had not been phagocytized by the Sertoli cells. Sertoli-spermatid junctional specializations were usually applied to the heads of the mature spermatozoa. The unreleased spermatozoa often appeared swollen with accumulated fluid located in the subacrosomal space. The accumulation of subacrosomal fluid in the unreleased spermatozoa seems to result from the absence of tubulobulbar complexes. That is, when tubulobular complexes fail to form the normal flow of cytoplasm into the tubulobular complexes is blocked resulting in an accumulation of fluid around the nucleus. Inhibition of spermiation may result from the absence of tubulobulbar complex formation. It is postulated that the tubulobulbar complex functions to transfer a chemical trigger from the maturing spermatid into the Sertoli cell. This chemical trigger may initiate the disappearance of the Sertoli-spermatid junctional specialization and induce spermiation.

Animals↗
PubMed1979

Interrelationships between Sertoli cells and germ cells in the Syrian hamster.

The interrelationships of the Sertoli cells and germ cells in the Syrian hamster were examined using the electron microscope. Demosome-like junctions were observed attaching Sertoli cells to spermatogonia and spermatocytes. In the region of the junctions dense plaques lay on the cytoplasmic surfaces of the plasmalemma of the opposing cells. Sertoli cell cytoplasmic filaments converged in the area of the junctions and inserted into the subsurface densities. Filaments were not observed associated with the subsurface densities of the germ cells. In the region of the junctions a 15...20 nm gap, filled with an attenuate amorphous substance, separated the plasmalemmata. Another attachment device termed "junctional specialization" occurred between Sertoli cells, and preleptotene spermatocytes and all successive developmental steps in the germ cell line in the hamster. The junctional specializations consisted of a mantel of Sertoli cell cytoplasmic filament lying subjacent to the Sertoli cell plasmalemma and an opposed cisterna of the endoplasmic reticulum. In stages VII-VIII preleptotene supermatocytes were observed in transit from the basal compartment to the adluminal compartment. While Sertoli-Sertoli junctions adluminal to the spermatocytes remained intact, typical Sertoli-Sertoli junctions formed between opposed Sertoli cell processes basal to the spermatocytes. It is proposed that, during the passage of spermatocytes in to the adluminal compartment, junctional specializations associated with preleptotene spermatocytes in the basal compartment migrate basal to the spermatocytes and contribute to formation of Sertoli-Sertoli junctions. Treatment of seminiferous tubules with hypertonic media was used to demonstrate that the junctional specializations function in cell-to-cell adhesion. Data indicated that these junctions function to retain the developing spermatids within the seminiferous epithelijm until the time of spermiation. At spermination the junctional specializations disappear and the spermatids drift off into the tubule lumen.

Animals↗
PubMed1978

Inhibition of spermiation in the Syrian hamster using dibutyryl cyclic-AMP.

Young adult male Syrian hamsters were given intraperitoneal injections of 50 mg dibutyryl cyclic AMP twice daily for a period of three days. On the fourth day the animals were sacrificed and their testes were processed for light and electron microscopy. The results indicate that the mature spermatozoa were retained within the seminiferous epithelium after the stage in the seminiferous cycle in which spermiation normally occurs. The unreleased spermatozoa were ultrastructurally normal. Typical Sertoli-spermatid junctional specializations remained associated with the retained spermatozoa. These findings indicate that normally spermiation is initiated by the disappearance of the junctional specializations. In addition, the present results demonstrate that spermiation can be controlled.

Animals↗
PubMed1977

Testicular involution following optic enucleation: the Leydig cell.

The testes of Syrian hamsters underwent pronounced involution within six weeks after blinding. The seminiferous tubules were devoid of all stages of spermatid development and mature spermatozoa were absent from the tubule lumina. The diameter of of the Leydig cells was 25% less than that of controls. Examination with the electron microscope revealed thick bundles of collagen fibrils interspersed between Leydig cells and surrounding Leydig cells in the blinded hamsters. The Leydig cell nuclei were shrunken and highly infolded. Lipid droplets that were often seen in normal Leydig cells were absent in the involuting Leydig cells. The size of the Golgi complex and the amount of smooth endoplasmic reticulum were reduced. Results of the present experiment confirm that inactivity of the Leydig cells is the reason for the decline in serum testosterone levels in blinded hamsters.

Animals↗
PubMed1977

Testicular involution following optic enucleation. An ultrastructural and cytochemical study.

The testes of adult male Syrian hamsters underwent involution within six weeks after optic enucleation. The diameter of the seminiferous tubules was 39% less than controls. Sertoli cells, spermatogonia, and primary spermatocytes were still present, but all steps of spermatids were completely absent from the involuted testes. Lipid droplets filled the Sertoli cell cytoplasm and often encroached upon the nucleus. Sertoli cells had sparse mitochondria and smooth endoplasmic reticulum, but Golgi cisternae were abundant. Typical Sertoli-Sertoli junctions attached contiguous Sertoli cells. With lanthanum tracers it was demonstrated that these junctions were impenetrable; therefore, the blood-testis barrier was deemed intact. Irregularly shaped protrusions often arose from the peritubular tissue and extended inward toward the seminiferous epithelium, often displacing the cytoplasm of the Sertoli cells and spermatogonia. The core of these protrusions consisted of irregular extensions of myoid cell cytoplasm surrounded by the myoid cells' basal lamina. External to the myoid cell basal lamina were bundles of collagen filaments with the basal lamina of the seminiferous epithelium forming the outermost layer of these protrusions. The apices of the Sertoli cells gave rise to numerous leaf-like processes that extended into and obliterated the lumen of the tubules. The Sertoli cell basal cytoplasm often contained phagocytized degenerating germ cells that appeared to give rise to the lipid droplets that filled the Sertoli cell cytoplasm. Acid phosphatase rich lysosome-like organelles were seen fusing with the degenerating germ cells and lipid droplets. The degenerating germ cells also were shown to contain acid phosphatase activity.

Acid Phosphatase↗
PubMed1977

Stability of the intra-epithelial component of the blood-testis barrier in epinephrine-induced testicular degeneration in Syrian hamsters.

Adult male Syrian hamsters were given daily intraperitoneal injections of epinephrine (1.0 mg/kg) and papaverine, a vasodilator, (60 mg/kg) for a period of ten days. After the treatment period, lanthanum and horseradish peroxidase tracer studies were used to examine the intra-epithelial component of the blood-testis barrier. Degenerating tubules often exhibited only Sertoli cells and spermatogonia, or Sertoli cells alone. Sertoli cell processes in the degenerating tubules often arched out from the main cell body to make contact with other Sertoli cell processes, forming a series of vacuole-like spaces in the germinal epithelium, adluminal to the Sertoli-Sertoli junctions. At the site of contact between these arching Sertoli cell processes one to eight tight junctions had formed with hexagonal arrays of Sertoli cell cytoplasmic filaments located immediately adjacent to these junctions. Cisternae of the Sertoli cell endoplasmic reticulum lay deep to the layer of cytoplasmic filaments. It appeared that these junctions had originated after the expulsion of the germinal elements of the seminiferous epithelium. Penetration of the tracers in the degenerating seminiferous tubules was prevented by what appeared to be normal Sertoli-Sertoli junctions located between apposed Sertoli cells, adluminal to the remaining spermatogonia when these resisted degeneration, or just adluminal to the basal lamina in those tubules in which spermatogonia were absent.

Animals↗
PubMed1976

Light and electron microscopic localization of ATPase in normal and degenerating testes of Syrian hamsters.

The distribution of Mg++-activated ATPase was determined with light and electron microscopy in normal and degenerating seminferous tubules. In the normal animals ATPase was localized in the interface between spermatids and Sertoli cells, in association with the cytoplasmic filaments contained within Sertoli cell processes, and in the lymphatic endothelium. ATPase activity increased in degenerating tubules as observed by light microscopy. Electron microscopic investigations of the degenerating tubules which contained only spermatogonia and Sertoli cells revealed reaction product on the outer surface of the Sertoli cell processes and within the interface between adjacent Sertoli cells. Reactaction product was also observed in the Sertoli cell processes between the cytoplasmic filaments and the cell membrane. Where filaments were absent in Sertoli cell processes, no reaction product was observed. These electron microscopic studies indicate that the increase in ATPase activity in testicular degeneration is probably a relative increase due to a loss of the germinal elements of the tubular epithelium and subsequent apposition of the Sertoli cell processes. We speculate that the ATPase activity localized within the Sertoli cell processes may be involved in providing an energy source for filament motility.

Adenosine Triphosphatases↗