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

Proximity frequencies of autosomic bivalents to the XY pair in metaphase I human spermatocytes were evaluated, showing a nonrandom bivalent distribution and a relative position pattern notably preserved from pachytene to metaphase I.


Zaida Sarrate, Ph.D., Joan Blanco, Ph.D., Francesca Vidal, Ph.D.

Vol 98, Issue 5, Pages 1241-1245



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


Proximity frequencies of autosomic bivalents to the sex bivalent were evaluated with the analysis of meiotic preparations combining sequentially standard techniques and Multiplex FISH.


Assisted Reproduction Centers and Universitat Autònoma de Barcelona.


Thirty-seven men consulting for fertility problems.


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.


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


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, in spite of different infertility etiology, proposes that nuclear organization pattern remains largely unaffected even if spermatogenesis is compromised.

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