[Studies on expression and location of VEGF protein in rat testis and epididymis]

In order to investigate the function of vascular endothelial growth factor (VEGF) in the male reproductive system, we examined the expression and localization of VEGF protein in adult rat testis and epididymis with the immunohistochemical method and PAS stain and western blots. The results showed that the VEGF protein (about 45 kD) was present in the rat testis and epididymis. The VEGF immunoreactive particles were localized in the cytoplasm of spermatids, Sertoli cells and Leydig cells with negatively stained nuclei. The expression pattern of the spermatids was different in the 14 stages of epithelial cycle, and the strong immunopositive reaction was mainly in the forming/formed acrosome of round/elongated spermatids and spermiogenic residual bodies. In the epididymis, the region-specific and cell-specific expression and localization of VEGF protein was shown in the epididymal epithelium. In the initial segment, the VEGF protein was presented in the whole epithelial cells and the immunoreactive particles were localized in the supranuclear region of the cells. Except for a few principal cells and basal cells, counter-staining of PAS stain proved that the immunoreactive cells were clear cells in the caput, corpus, and cauda epididymis. And the immunoreactive particles were localized in the different region of the cytoplasm of clear cells, some were in the supranuclear region, some were filled in the whole cytoplasm, and some were secreted out of the cells along the free border. The positive acrosomes of the spermatozoa were only seen in the lumen of the proximal epididymis. No expression was detected in the interstitial blood vessels and the capillaries of the testis and epididymis. The present results indicate that VEGF protein may play an important role in the process of the spermatogenesis and spermiogenesis, especially in the acrosomal developing process. VEGF may also be related to the sperm maturation in the epididymis.