Chromosome Research

, Volume 5, Issue 7, pp 467–474

The prevalence of a YY synaptonemal complex over XY synapsis in an XYY man with exclusive XYY spermatocytes


DOI: 10.1023/A:1018469030537

Cite this article as:
Solari, A.J. & Rey Valzacchi, G. Chromosome Res (1997) 5: 467. doi:10.1023/A:1018469030537


An infertile XYY man was studied by synaptonemal complex analysis of microspread spermatocytes and by quantitation of germ cells in semithin sections. All the 74 spermatocytes micrographed have an XYY constitution, and the biopsy shows a homogeneous arrest of spermatogenesis at the spermatocyte/young spermatid stages. The overwhelming majority (86%) of spermatocytes showed a Y—Y bivalent plus a univalent X. The Y—Y bivalent is totally synapsed in 48% of the cells. In the remaining cells, the YY bivalent has an average synaptic segment covering 43% of its length that always includes Yp. Another 9% of the spermatocytes showed an XYY trivalent and 4% of the spermatocytes showed univalence of the three gonosomes. Progression through all the pachytene substages was observed in cells with the two main synaptic configurations, but a high level of germ cell death was observed at or immediately after the meiotic divisions. The prevalence of Y—Y synapsis arises from the longer homologous region and the higher speed of pairing between the two Y chromosomes. Germ cell death is probably related to the univalence of the X chromosome. Synaptic competition between three gonosomes seems to be similar to that found in triploid birds but is somewhat different from that of XYY mice.

synaptonemal complexesXYY menXYY spermatogenesis arrestYY bivalentY disomy

Copyright information

© Chapman and Hall 1997

Authors and Affiliations

  1. 1.Facultad de MedicinaCentro de Investigaciones en ReproduccionBuenos AiresArgentina