Analysis Of The Spermatocyte Meiotic Recombination In Male

Infertility is a major health problem that affects 10%-20% of couples, and about a half is attributed to male factors. Despite the obvious clinical significance of human male infertility, the mechanisms of spermatogenic failure caused by meiotic recombination errors in humans are inadequately known at present.During the prophase of meiosisⅠ,homologous recombination plays a crucial role in the proper segregation of homologous chromosomes. Altered recombination may be an important risk factor for non-disjunction,which in turn contributed infertility. However,recently developed immunofluorescence methods,which enable us to directly view meiotic recombination events during gametogenesis,have revolutionized our understanding of human spermatogenesis. Using the spreading technique to prepare synaptonemal complexes from spermatocytes and antibodies against SCP3(synaptonemal complexe protein) , MLH1(DNA mismatch repair protein), and CREST to display lateral elements of the SCs, recombination sites and centromeres. The proportion of pachytene cells in 5 fertile men was 67-78%. The mean recombination frequency was 46.1±3.9, ranging 34-61, which is significantly different among donors. Abnormal synapsis such as gaps (discontinuities) and splits (unpaired chromosomes regions) were noted, with the mean frequencies being14.3% and 2.9% per cell, respectively. There was remarkable variation in the recombination frequencies among fertile individuals.There is little information regarding recombination behaviors and synaptic patterns during meiosis I in men with reciprocal tranlocation. We applied immunostaining for SCP3, MLH1 and CREST on biopsies from a t(1;21) carrier to identify synapsis and recombination .The t(1;21) carrier shows a high ratio of SCs with gaps. The MLH1 rates in XY pair were significantly reduced in the translocation carrier than that in the control group. These results suggest that synaptic integrity of translocated chromosome may affect the global synapsis, recombination frequency of XY pair, thus determine fertility status in men.