The presence of a caput epididymidis in congenital absence of the vas deferens.

Experience with 2 patients stimulated a review of the literature on congenital absence of the vas deferens in 133 cases. Bilateral absence was more common and occurred in 80 per cent of the cases, and a caput epididymidis was said to be present in at least 88 per cent. Information concerning the epididymis was lacking in 8.9 per cent of the cases. Two probable explanations for this common clinical finding are offered. Embryologic studies have shown that the caput, unlike the rest of the epididymis, can develop from genital ridge derivatives mainly. This clinical-embryological consideration refutes the common belief that the vas deferens and epididymis as a whole are of mesonephric duct origin. A second, independent factor is the selective blood supply of the caput in some cases. In these cases the caput is preserved by a branch of the testicular artery, perforating the tunica albuginea from within outwards, instead of a branch of the spermatic artery originating from the extratesticular portion of the testicular artery.