Use of sex chromosome bivalent pairing in spermatocytes of nonobstructive azoospermic men for the prediction of successful sperm retrieval.

Objective: To find the most informative method of XY bivalent detection for spermatozoa presence in testicular tissue of nonobstructive azoospermic men.

Design: Prospective study.

Setting: Institute for the Study of Fertility, affiliated with a university medical faculty.

Patient(s): Thirty-five men with azoospermia, divided into subgroups: complete maturation arrest (n = 10), mixed atrophy (n = 14), and obstructive azoospermia (n = 11).

Intervention(s): Testicular tissue biopsies for sperm extraction.

Main Outcome Measure(s): Histopathologic and cytology analyses and the presence of XY bivalent formation by fluorescence in situ hybridization probes for centromere and subtelomere regions. Immunostaining of gamma-H2AX for sex body (SB) identification was also performed.

Result(s): Percentage of spermatocytes with X-Y pairing, determined by the paired short arms pseudoautosomal region, was significantly higher than percentage of spermatocytes with long arm telomeres in proximity in all three groups. The parameter of q telomeres in proximity was the most sensitive index to distinguish one group from the other. Stained SB by gamma-H2AX was found to be the most informative for the prediction of successful sperm retrieval.

Conclusion(s): Alignment of the X and Y axes that occurs in the late zygotene stage probably precedes the stage in which the SB is stained by gamma-H2AX. Consequently, because of the nonhomogeneity of the testis, when histology raises suspicion of complete maturation arrest percentage of spermatocytes with stained SB is the most informative parameter for sperm presence on sperm retrieval.