Effect of simulated microgravity on testicular structure of the adult albino rat: histological and histochemical study

As space flight becomes more commonplace, the influence of physiological and histological changes associated with the microgravity environment become of greater concern. The aim of this work is to determine the effect of simulated microgravity on the testis of rats and to evaluate the possibility of spermatogenesis failure in space environment. Thirty adult male albino rats were used in this experiment and were divided into control and experimental groups. The rats of control group remained nonsuspended without inguinal canal ligation. The experimental group was divided into three subgroups, the rats of subgroup I were tail-suspended with inguinal canal ligation for one week. The rats of subgroup II were tailsuspended with inguinal canal ligation for six weeks. The rats of subgroup III [recovery] were tail-suspended with inguinal canal ligation for six weeks then left without suspension for another six weeks. Paraffin sections were stained with hematoxylin and eosin and Periodic Acid Schiff. The semithin sections were stained with toluidine blue. Frozen sections were cut for demonstration of succinic dehydrogenase enzyme. The results of the present study demonstrated few abnormalities in some seminiferous tubules of subgroup I. In subgroup II, the seminiferous epithelium revealed more pronounced destructive changes in which most of the germ cells were depleted and proliferation of interstitial cells of Leydig was also noticed. The seminiferous epithelium in the recovery subgroup looked almost normal containing full complement of germ cells. These findings have significant reflections concerning serious effects of long-term exposure to microgravity on the testes of mammals including human beings

Effect of food consistency on the structure of parotid gland of adult male albino rat: histological and immunohistochemical study

Eighteen adult male albino rats were employed to investigate the histological, immunohistochemical and ultrastructural changes in the parotid gland after feeding with liquid diet. The purpose of this study was to demonstrate the significance of mastication on the structure of parotid glands. The rats were divided into three groups, six rats each. Group I [control]: the animals were fed the hard and liquefied diet. Group II: the animals were fed a liquefied diet only for ten days. Group III: were fed the liquid diet for ten days then the hard diet for one week. After anesthesia, small pieces of the parotid gland were processed for paraffin sections and stained with hematoxylin and eosin stain, and avidin-biotin complex technique for alpha-smooth muscle actin. Ultrathin sections were prepared for electron microscopic examination. After liquid diet feeding [Group II], the parotid gland revealed disorganized acini and change in the nuclear shape in the acinar cells. Group III revealed multiple round clear areas in the cytoplasm of acinar cells with large rounded nuclei and some mitotic figures. Immunohistochemically, the liquid diet feeding has resulted in a higher concentration of actin-positive cells in the glandular tissue than in the control group. These actin-positive reactions have later been decreased and appeared as a few positive reactions at the acinar periphery after hard diet re-feeding [Group III]. Ultrastructurally, after liquid diet feeding, the acinar cells showed an apparent decrease in the number of secretory granules. In group III, the heterogeneous secretory granules were seen in some acinar cells. These results demonstrate that the morphology of the parotid serous acini depends on the masticatory reflex stimulation, and suggest that mastication plays an important role in the regeneration of the parotid glands