Comparative study between phase contrast and differential interference contrast microscopies for evaluation of frozen bull semen

Abstract

Two hundred ampules of frozen bull semen were evaluated for per cent acrosomal pathology and major and minor defects of spermatozoa. The ampules referred to 4 groups of 50 each, corresponding to semen frozen in 1975, 1976, 1977 and 1978. Semen examinations were made after thawing and after being placed in a 38°C water bath for 5 hours (Slow Thermo resistance Test) or in a 45°C water bath for 1 hour (Quick Thermo resistance Test). Analysis of variance showed highly significant differences (P<.01)between phase-contrast and differential interference contrast microscopies for evaluation of acrosomal pathology and major defects of spermatozoa. For minor defects analysis of variance did not show statistical differences between the two technics employed.