Ductuli efferentes in the epididymis of boar, goat, ram, bull, and stallion.

Dutculi efferentes were studied by microdissection and histologic methods in 2 boar, 6 goat, 5 ram, 25 bull, and 19 stallion epididymides. On the basis of the present findings and the data of others and relating them to the total number of specimens examined in each species, an estimate (narrow range) was made of the minimal-maximal numbers of efferent ductules as follows: dog 13 to 15; cat 14 to 17; boar 14 to 16; goat 18 to 19; ram 17 to 20; bull 13 to 16; and stallion 14 to 17. The histologic appearance of the efferent ductules of the bull, including measurements of their diameter, lumen, and epithelium, was briefly described. Attention was focused on the presence of blind-ending ductules, because it was thought that they might be a factor in the cause of spermiostasis. Blind-ending ductules were found in 1 of 2 porcine, 1 of 6 caprine, 2 of 5 ovine, 8 of 25 bovine, and 13 of 19 equine ductules per affected male were 4 in the boar, 1 in the goat, 2 to 3 in the ram, 1 to 5 in the bull, and 1 to 14 in the stallion. From our work, it appears that in the bull and stallion at least, blind-ending ductules were present in sufficient numbers to be considered a factor in spermiostasis and the infertility resulting from it.