Abstract:

Objective To compare the distribution and histochemical characteristics of extracellular matrix components in the testis between 4 Tibetan sheep and 5 small-tail Han sheep from plateau at the same age. Methods Histochemistry and transmission electron method were used to characterize the microstructure and ultrastructure of the two kinds sheep testis. Image-Pro Plus(IPP) statistics methods were used to identify the integrated absorbance for laminin(LN), type Ⅳ collagen(ColⅣ) and heparan sulfate proteoglycans(HSPG) distribution investigation by immunohistochemistry. Results The light microscopy observation showed that compared with the testis of the small-tail Han sheep from plateau, the collagen and reticular fibers were richer in interstitial of the Tibetan plateau sheep. The periodic acid-schiff(PAS) and Alcian blue-periodic acid schiff(AB-PAS) staining positive reactions were more obvious in interstitial basement and blood capillary of the Tibetan plateau sheep testis. Immunostaining analysis showed that the Col Ⅳ was present strongly in the seminiferous epithelium of both the Tibetan plateau sheep and the small-tail Han sheep. The expression of LN in the Sertoli cells and peritubular myoid cells of the Tibetan plateau sheep testis was weak but moderately positive in the Sertoli cells, the Leydig cells and peritubular myoid cells of the small-tail Han sheep testis. In the both kinds of sheep testis, the expression of HSPG was especially strong in the peritubular myoid cells but weak in the Sertoli cells and Leydig cells. The integrated absorbance of Col Ⅳ and LN expression was significantly lower in testis of the Tibetan sheep than the smalltail Han sheep (P<0.01）, but the average absorbance of HSPG expression was markedly higher than it (P<0.01). Electron micrographs of portion of the seminiferous tubule in the both of the testis showed elaborately developed tunicae propria with a well defined epithelial basal lamina and a distinct layer of typeⅠcollagen fibrils. The collagen fibrils were found around the interstitial blood capillaries and the abundant Lipid droplets in the Leydig cells of the small-tail Han sheep testis from plateau. Conclusion In plateau environment, the connective tissue in the tunicae propria and interstitial tissue of the Tibetan sheep testis is more abundant, and partly affect the development of the seminiferous epithelium. The AB-PAS positive reaction in interstitial basement and the wall of blood capillary in the Tibetan plateau sheep testis are closely related to the secretory function of the Leydig cells. The integrated absorbance of LN expression is significantly higher and HSPG is lower markedly in testis of the smalltail Han sheep testis, which is very important to the development degree of seminiferous epithelium.

Key words: Testis, Exreacellular matrix, Histochemistry, Immunohistochemistry, Tibetan plateau sheep, Small-tail Han sheep