Hypo-osmotic swelling test as a predictor for nuclear maturity of sperms assessed by aniline blue staining

Jee, Byung Chul; Moon, Shin Yong

Abstract

OBJECTIVE
Many cases of fertilization failure after ICSI is attributed to decondensation defect of sperm head, therefore, selection of sperm with well-condensed, fully-matured nucleus is critical for successful fertilization. During mammalian spermiogenesis, replacement of the somatic histones by protamines allows normal sperm nuclear condensation. The degree of condensation can be shown with the aid of acidic aniline blue staining, which is able to discriminate between lysine-rich histones and arginine- or cysteine-rich protamines. The objective of this study was to investigate the possible relation between nuclear maturity of human sperm and hypo-osmotic swelling patterns. Hypo-osmotic swelling test is very simple and convenient test to measure functional integrity of human sperm membrane, and each already tested sperms can be used for fertilization.
METHODS
For assessment of sperm nuclear maturity, aniline blue staining was performed on the slides, already undergone hypo-osmotic swelling test in 5 subfertile patients with abnormal semen parameters and 8 fertile donors. After 3 hours swim-up, these procedures were repeated in each cases.
RESULTS
Sperms with negative aniline blue were significantly increased after swim-up in each group. There was a significant increase in the proportion of negative aniline blue in sperms with swelling patterns(e+f+g) compared to sperms with non-swelling patterns(a), except swim-up group in subfertile patients.
CONCLUSION
Choosing the swelling patterns, rather than non-swelling sperms after hypo-osmotic test may be beneficial for the selection of sperms with well-condensed, mature nucleus and intact membrane.