Synapsis and meiotic recombination analyses: MLH1 focus in the XY pair as an indicator.

BACKGROUND Anomalies in meiotic prophase I have been related to partial or total meiotic arrest. These anomalies include an abnormal synaptic process, resulting in disorders in meiotic recombination. METHODS In the present study, we analyse primary spermatocytes from 12 infertile men (four with non-obstructive azoospermia, six with oligoastenoteratozoospermia, one with astenoteratozoospermia and one normozoospermic) and five control fertile donors using immunocytological techniques for synaptonemal complex, meiotic recombination and centromeric proteins. RESULTS Mean numbers of MLH1 foci per cell, frequencies of cells presenting an MLH1 focus in the XY pair and percentages of cells affected by abnormal synaptic patterns (gaps and splits) are reported for each of the infertile patients and control men. A positive correlation between the frequency of cells showing a recombination focus in the XY pair and the number of autosomal recombination foci per cell is found. CONCLUSIONS Reduced recombination in the XY pair and an increased number of cells affected by gaps may explain some idiopathic male infertility cases. The results suggest that recombination in the XY pair could be an indicator for general recombination frequency and for a successful meiotic process.