Segmental aplasia of the ductus deferens in the boar.

Abstract

The ductus deferens and ductus epididymidis develop from the mesonephric duct (Wolffian duct) [ 121. Aplasias of either or both derivatives have been described in bulls [ 1-3, 8, 9, 111, dogs [6, 10, 111, rams [4], and stallions [7]. The incidence of these aplasias has been suggested only for cattle in reports from Denmark [l , 31. There is only one report of the condition in boars [9]. At a Chicago abattoir that slaughters over 1000 boars per day, principally from the surrounding five states, 326 boars were selected randomly in seven visits over a 14-month period. Scrota1 contents were examined carefully. Two cases (0.61%) of segmental aplasia were found. Boar 141 had a body weight of 139.4 kg (based on a standard 60% dressing percentage for this abattoir). Only the right testis and epididymis were in the scrotum. The testis weighed 475 g and the epididymis 195 g. The mean testicular weight and epididymal weight f standard deviations for normal boars of this size were 287.0 f 57.4 g and 66.5 * 19.5 g respectively (unpublished data). The cauda epididymidis of boar 141 was particularly enlarged. Only the initial portion of the ductus deferens was present. Both the ductus deferens and cauda epididymidis were firm. Section of the cauda resulted in an explosive release of epididymal fluid. This fluid was sampled, fmed in 2% buffered glutaraldehyde (w/v) and later examined microscopically. Of the dense population of spermatozoa, 76% had loose heads, predominantly without acrosomes, and an additional 15% had abnormal acrosomes. No macrophages or other inflammatory cells were seen. Boar 325 had a body weight of 124.08 kg. Again, only the right testis and epididymis were in the scrotum. The total specimen (testis, epididymis, and funiculus spermaticus) (fig. I ) weighed 396 g. The testis had an intracapsular cyst 1.2 cm in diameter that contained clear fluid and was located 0.7 cm caudomedial to the caput epididymidis (fig. I). Otherwise the testis was normal, as were both the caput and corpus epididymidis. The cauda epididymidis, however, was enlarged and again only the initial portion of the ductus deferens was present. Both the ductus deferens and cauda epididymidis were firm. The ductus deferens had a blind end with a maximum external diameter of 0.5 cm. Both of these boars had segmental aplasias of the ductus deferens. The dilated ductus deferens, firm enlarged cauda epididymidis, and deterioration of spermatozoa in the epididyma1 fluid are evidence of spermiostasis. The duct was open throughout the epididymis and its connection to the testis, and there was spermatogenesis. The small cyst in boar 325 probably was derived from the appendix of the epididymis, a blind cranial remnant of the mesonephric duct [ 11, 121. Its clear, watery content showed that it had no connection to the efferent ductules. In the boar previously described [9], aplasia of the ductus deferens was combined with segmental aplasia of the epididymis. As has also been reported in the bull [ 1, 8, 9, 1 11, dog [6, 101, and ram [4], in such an instance the cauda epididymidis is not enlarged. Instead, it may