血管内皮生长因子蛋白在大鼠睾丸和附睾的表达和定位研究

为探讨血管内皮生长因子(VEGF)在雄性生殖系精子发生发育和成熟过程中的调控作用,应用免疫组化、Periodic acid-Schiff(PAS)染色及蛋白质免疫印迹技术,检测VEGF蛋白在成年大鼠睾丸和附睾的表达和定位情况。Western-blots显示,在大鼠睾丸和附睾内均有VEGF蛋白(约45kD)的表达;免疫组化显示,睾丸内VEGF见于圆形和长形精子细胞、Sertoli细胞和Leydig细胞,免疫阳性产物位于细胞质内。精子细胞的VEGF表达伴随精子细胞顶体发育的全过程,精子残余体呈强阳性。附睾内VEGF表达于附睾管上皮,且有区域和细胞特异性。附睾起始段的所有上皮主细胞内都有VEGF阳性颗粒;头、体、尾各段的VEGF阳性细胞多数与含PAS阳性颗粒的细胞重合,证明为亮细胞;近端附睾的管腔内可见精子头部呈VEGF阳性染色。睾丸、附睾间质血管内皮为VEGF阴性。上述结果表明,VEGF蛋白可由生殖细胞和附睾管上皮细胞直接产生,它可能以自分泌和/或旁分泌的形式共同作用于睾丸和附睾的生殖细胞和血管内皮,直接或间接影响精子的发生、发育和成熟过程,特别是精子顶体的形成过程,并可能与精子在附睾内的成熟有关。

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.