Immunohistochemical localization of cyclooxygenase-1 and cyclooxygenase-2 in the human fetal and adult male reproductive tracts

The first rate-limiting step in the conversion of arachidonic acid to PGs i s catalyzed by cyclooxygenase (Cox). Two isoforms of Cox have been identifi ed, Cox-1 (constitutively expressed) and Cox-2 (inducible form), which are the products of two different genes. In this study we describe the immunohi stochemical localization of Cox-1 and -2 in the human male fetal and adult reproductive tracts. There was no Cox-1 expression in fetal samples (prosta te, seminal vesicles, or ejaculatory ducts), and only minimal expression in adult tissues. There was no expression of Cox-2 in the fetal prostate. In a prepubertal prostate there was some Cox-2 expression that localized exclu sively to the smooth muscle cells of the transition zone. In adult hyperpla stic prostates, Cox-8 was strongly expressed in smooth muscle cells, with n o expression in the luminal epithelial cells. Cox-a was strongly expressed in epithelial cells of both fetal and adult seminal vesicles and ejaculator y ducts. The Cox-2 staining intensity in the fetal ejaculatory ducts during various times of gestation correlated with previously reported testosteron e production rates by the fetal testis. These data indicate that Cox-2 is t he predominant isoform expressed in the fetal male reproductive tract, and its expression may be regulated by androgens. The distinct cell type-specif ic expression patterns of Cox-8 in the prostate (smooth muscle) vs, the sem inal vesicles and ejaculatory ducts (epithelium) may reflect the different roles of PGs in these tissues.