Adult Male Syrian Hamsters Research Articles

Refractoriness to the antigonadotrophic effects of melatonin in male hamsters and its interruption by exposure of the animals to long daily photoperiods

Exposure of adult male Syrian hamsters to artificially shortened photoperiods in the laboratory was followed by gonadal involution. Return of these animals to long days (light:ddark cycles of 14:10) resulted in regrowth of the reproductive organs, following which the animals were refractory to the normally antigonadotrophic effects of daily melatonin injections given late in the afternoon. When hamsters were kept under naturally shortening photoperiods beginning on October 19, their reproductive organs involuted and remained infantile until the following spring when they again recrudesced to adult size. These animals too were refractory to the inhibitory effects of daily afternoon melatonin injections. The refractory period to melatonin was interrupted by exposure of the animals to long days for 22 weeks.

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.

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.

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.

Alkaline Phosphatase Localization in Testicular Degeneration Induced by Epinephrine Treatment

Young adult male Syrian hamsters (80-130g) were used in these studies. Six control animals received daily intraperitoneal injections of sterile saline (0.1 ml) for a period of ten days. Six experimental animals received daily intraperitoneal injections of the vasodilator papaverine (60 mg/kg) five minutes prior to an intraperitoneal injection of epinephrine (1.0 mg/kg) for 10 days. After treatment testes were fixed by retrograde perfusion into the abdominal aorta with 3% cacodylate buffered glutaraldehyde and then processed for electron microscopic localization of alkaline phosphatase. In control animals electron microscopic investigations (Fig. 1) demonstrated marked reactivity in the basal laminae of the seminiferous tubules and in both the internal and external basal laminae of the myoid cells.

Primary and secondary immune response kinetics in the Syrian hamster.

Numbers of direct and indirect plaque-forming cells (pfc) per 10<sup>6</sup> spleen cells, total and mercaptoethanol-resistant hemolysin and hemagglutinin activity have been determined in adult male Syrian hamsters at different times after primary and secondary intraperitoneal injection of 1×10<sup>10</sup> sheep red blood cells (SRBC). Only a high antigen dose was sufficient for stimulating a uniform immune response. The kinetics of the primary response at the cellular and serum level corresponds in general to that of the mouse and other laboratory animals. In the secondary response the direct pfc/10<sup>6</sup> spleen cells and total serum hemolysin and hemagglutinin concentrations were higher than in the primary response and the pfc and serum antibody curves declined rapidly again after reaching their peaks.