Acrocentric bivalents positioned preferentially nearby to the XY pair in metaphase I human spermatocytes.

Objective: To analyze whether the preferential proximity between acrocentric bivalents and the XY pair described at pachytene was maintained in metaphase I human spermatocytes.

Design: Proximity frequencies of autosomic bivalents to the sex bivalent were evaluated with the analysis of meiotic preparations combining sequentially standard techniques and multiplex fluorescence in situ hybridization.

Setting: Assisted reproduction centers.

Patient(s): Thirty-seven men consulting for fertility problems.

Intervention(s): Unilateral testicular biopsies.

Main Outcome Measure(s): Proximity frequencies analysis to the XY pair, evaluated individually and grouping bivalents, was carried out using a logistical regression model with repeated measures.

Result(s): Bivalents 22 and 15 were observed more frequently near to the sex bivalent than the others. Significant interindividual differences were not observed.

Conclusion(s): Results suggest that bivalents distribution to the metaphase plate is nonrandom. The maintenance of the acrocentric chromosomes' proximity to the sex bivalent from pachytene to metaphase I would indicate that the relative bivalents position would be notably preserved. The observation of non-interindividual variability, despite different infertility etiology, suggests that the nuclear organization pattern remains largely unaffected even if spermatogenesis is compromised.