OBJECTIVETo study the expressions of the vascular endothelial growth factor (VEGF) and its receptor fms-like tyrosine kinase-1 (Flt-1) in the testis, epididymis and epididymal sperm of adolescent rats and explore the functions of both the proteins in the male reproductive system.

METHODSThe expressions of VEGF and Flt-1 were detected in 20 adolescent SD rats, immunohistochemical staining used for both the testis and the epididymis and immunofluorescent staining for sperm.

RESULTSVEGF and Flt-1 proteins were specifically present in the testis, epididymis and sperm. In the testis, VEGF immunoreactive particles were localized in the cytoplasm of spermatogenic cells, the developing acrosome of spermatids, Sertoli cells and Leydig cells, while Flt-1 expressed mainly in the developing acrosome of spermatids and Leydig cells. In the epididymis, the cell-specific and region-specific expressions of VEGF and Flt-1 proteins were observed in the principal cells of epididymal epithelia, VEGF in the whole epididymis, while Flt-1 only in the caput and cauda segments. Both VEGF and Flt-1 were localized in the acrosome of the sperm head as well as in the neck, middle and principal segments of the sperm tail.

CONCLUSIONThe specific expression patterns of VEGF and Flt-1 in the rat testis, epididymis and sperm indicate that they may independently or collectively affect spermatogenesis and spermiotelcosis in either an autocrinological or a