Analysis of the functional and nuclear integrity of human spermatozoa.

The analysis of semen quality and sperm function has added a new dimension to the evaluation of male infertility. In the present investigation, some recent techniques were used to assess the nuclear, membrane, and acrosomal integrity of spermatozoa from semen of 15 subfertile males with low sperm count and motility. In the infertile semen, the live-to-dead ratio and percentage of spermatozoa showing swelling in hypoosmotic solution was lower than normal but correlated positively with the motility of spermatozoa (r = .85). Staining the spermatozoa with silver nitrate, using a modified technique developed in our laboratory, revealed a higher percentage of morphologically abnormal spermatozoa, in particular, with loss of acrosomal integrity in the subfertile males. Moreover, the percentage of green-fluorescing "fertile" spermatozoa, with intact double-stranded DNA (acridine orange fluorescence), was lower than normal, which correlated with the reduction in sperm nuclear DNA content. A low correlation was obtained between motility and the percentage abnormal spermatozoa (r = .44) and motility and percent green sperm (r = -.28), suggesting that both tests evaluate sperm functional properties independent of motility. The new parameters, assessed with recent techniques, indicate poor sperm fertilizability, which may therefore contribute to the low fertility of the cases studied.