Effect of vasectomy on P34H messenger ribonucleic acid expression along the human excurrent duct: A reflection on the function of the human epididymis

Sperm surface proteins involved in fertilization can be added or modified d uring epididymal transit. P34H, a human epididymal-sperm protein, appears o n the sperm acrosomal cap in the distal caput-proximal corpus epididymis. I n previous studies, it was shown that P34H is present on spermatozoa in men of proven fertility, is absent in 50% of men presenting with idiopathic in fertility, and that a high proportion of men with normospermic vasovasectom y produce spermatozoa deficient in this sperm surface protein. B34H mRNA wa s expressed in the principal cells of the epididymis of normal men, predomi nantly in the corpus region. Recently, results coming from the assisted rep roductive technologies have questioned the importance of the human epididym is in sperm maturation. In order to understand the effect of obstruction on the physiological state of the human epididymis and its function in sperm maturation, we have analyzed the expression of P34H mRNA at the level of th e vas deferens and along the epididymis of normal and vasectomized men. In situ hybridization experiments showed that obstruction of the vas deferens alters the pattern of P34H mRNA expression compared with the tract of norma l tissues. The P34H transcript was detected in the proximal caput epididymi s of vasectomized men at a much higher intensity than that observed in the same region of normal tissues, being restricted to the principal cells of t he epididymal epithelium. Compared with the normal duct, the lumen of vasec tomized men was distended throughout the duct and the height of the epithel ium was maximal in the caput. P34H mRNA was detectable in vas deferens, was not affected by vasectomy, and a 912-base pair P34H transcript was restric ted to the epithelial cells of the vas deferens, Thus, using P34H as a mark er, these results show that vasectomy alters the pattern of gene expression along the human epididymis, and suggest that the vas deferens can be a maj or contributor to sperm maturation in certain situations.