Reproductive Capacity of Dairy Bulls. VII. Morphology of Epididymal Sperm

Abstract

Fourteen normal, mature bulls were sexually rested (SR), 5 ejaculated 6 or 7 times weekly, and 15 depleted (SR-D) before slaughter. The most pronounced treatment effects were lower (P< 0.01) percentages of unstained or live sperm (eosin-aniline blue) and sperm with distal protoplasmic droplets in the cauda epididymis for SR-D as compared with SR bulls. Unilateral vasectomy of 9 other bulls did not affect sperm morphology. Ignoring preslaughter treatment, average percentages of abnormal heads, abnormal midpieces, tailless sperm, bent or broken tails, coiled tails, proximal droplets, and distal droplets for the caput, corpus, and cauda for 85 epididymides were, respectively, 3.4, 2.5, 2.4; 1.1, 1.4, 0.8; 5.1, 10.1, 2.1; 4.4, 6.5, 8.4; 0.0, 0.8, 0.4; 44.4, 1.9, 2.1; and 7.5, 29.6, and 67.9%. Percentages of unstained sperm for the caput, corpus, and cauda for 40 epididymides were 77.0, 51.3, and 72.5. Eoslnophilia of sperm from the corpus epididymis apparently is associated with a change in membrane permeability, not cell death. The best morphological indication of impending cell death within the epididymis appeared to be a high incidence of bent or broken tails followed by complete loss of the tail and increased eosinophilia.