Evaluation of bovine spermatozoal morphologic features after staining or fixation.

Two experiments were conducted to evaluate effects of 3 stains and 2 fixatives on morphologic features of bovine spermatozoa. In experiment 1, the morphologic features of acrosomes of raw and incubated, extended spermatozoa were evaluated after staining with Hancock's Blom's or Wells-Awa's stains or after fixation with buffered glutaraldehyde. Evaluations were done of stained smears by bright field microscopy and of fixed, unstained preparations, by differential interference contrast microscopy, using wet mounts. Raw semen samples from 1st ejaculates of 80 bulls were evaluated. The percentage of spermatozoa with intact acrosomes averaged 83.5% in unstained preparations fixed in glutaraldehyde, compared with averages of 68.1, 74.5, and 67.4% for smears stained with Hancock's, Blom's, or Wells-Awa's procedures (P less than 0.01). From these results, it appeared that procedures for preparing stained smears were detrimental to acrosomes. Although counts for other acrosomal abnormalities differed (P less than 0.01) in each treatment, patterns were inconsistent. With incubated, extended spermatozoa from 57 bulls, glutaraldehyde-fixed, unstained samples had more (55%) intact acrosomes (P less than 0.01) than did samples stained with Hancock's or Blom's procedures (24.0 and 34.7%, respectively, but the former were not significantly different from Wells-Awa-stained smears (49.3% intact acrosomes). In experiment 2, several morphologic characteristics of spermatozoa from 15 1st ejaculates of 7 bulls were evaluated after staining with Hancock's or Blom's stains or after fixation in buffered glutaraldehyde or buffered formal saline fixatives. Higher counts (P less than 0.01) of head abnormalities were found in wet, unstained fixed preparations (4.83, 4.47, 7.87, and 7.93% respectively, for Hancock's, Blom's, glutaraldehyde, and formol saline methods). There were more (P less than 0.05) separated heads on stained, dry smears (1.43, 1.23, 0.47, and 0.47%, respectively, for Hancock's, Blom's, glutaraldehyde, and formol saline procedures). Fixation with buffered glutaraldehyde resulted in higher counts (P less than 0.01) of proximal protoplasmic droplets (2.47, 1.03, 0.67, and 1.43%, respectively, for glutaraldehyde, Hancock's, Blom's, and formol saline procedures). Although not significant, the same trend was observed for distal protoplasmic droplets...