Cytochrome P450 aromatase is a terminal enzyme in the conversion of androgen into estrogen. Presence of aromatase in male reproductive tract of some species is already demonstrated whereas its presence in male goat is not reported. In this study, immunolocalization of aromatase in the testis, proximal and distal ductus epididymis, ampulla, prostate and seminal vesicle tissues of five sexually mature male goats were investigated by immunoperoxidase technique. Mouse anti-aromatase polyclonal antibody and rabbit anti-mouse IgG antibody were applied in the assay as primary and secondary antibodies respectively. Two additional tissue sections were prepared from each tissue sample and served as negative controls. The first negative control was processed in the absence of primary antibody. In the second negative control section, the primary antibody was replaced by normal mouse serum. No positive staining was observed in the negative control sections whereas strong immunoperoxidase reaction were recorded in the tissue sections from sexually mature ram testis, considered as positive control in the assays. Cytochrome P450 aromatase antigen was detected in the Leydig cells, seminiferous tubule cells in different stages of spermatogenesis, epithelial cell cytoplasm of proximal ductus epididymis, seminal vesicle and prostate tissues of all animals tested. Meanwhile, goat distal ductus epididymis and ampulla were negative in the conducted immunoperoxidase assay. The highest aromatase antigen intensity was observed in the prostate samples, as shown by dark-brown positive reaction. This is the first evidence of aromatase presence in male goat reproductive tract including leydig cells, seminiferous tubules, epithelial cells of proximal ductus epididymis, seminal vesicle and prostate tissues. Considering the presence of estrogen receptors in male reproductive tract of most species including male goat, it seems that estrogen and its receptor are important for male reproductive tract
