Faculty Research 1990 - 1999

Synapsis and obligate recombination between the sex chromosomes of male laboratory mice carrying the Y* rearrangement.

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Male, Meiosis: ge, Mice, Mice-Inbred-Strains, Microscopy-Electron, Recombination-Genetic: ge, Sex-Chromosome-Abnormalities: ge, SUPPORT-NON-U-S-GOVT, SUPPORT-U-S-GOVT-P-H-S, X-Chromosome, Y-Chromosome: ul

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Cytogenet Cell Genet 1991;57(4):231-9


GM20919, RR01183, HD07065


The synaptic and recombinational behavior of the sex chromosomes in male laboratory mice carrying the Y* rearrangement was analyzed by light and electron microscopy. Examination of zygotene and pachytene X-Y* configurations revealed a surprising paucity of the staggered pairing configuration predicted from the distal position of the X pseudoautosomal region and the subcentromeric position of the Y* pseudoautosomal region. When paired at pachynema, the X and Y* chromosomes usually assumed configurations similar to those of typical sex bivalents from normal male laboratory mice. The X and Y* chromosomes were present as univalents in more than half of the early- and mid-pachytene nuclei, presumably as a result of steric difficulties associated with homologous alignment of the pseudoautosomal regions. When paired at diakinesis and metaphase I, the X and Y* chromosomes exhibited an asymmetrical chiasmatic association indicative of recombination within the staggered synaptic configuration. Both pairing disruption and recombinational failure apparently contribute to diakinesis/metaphase I sex-chromosome univalency, as most cells at these stages possessed X and Y* univalents lacking evidence of prior recombination. Recombinant X or Y* chromosomes were detected in all metaphase II complements examined, thus substantiating the hypothesis that X-Y recombination is a prerequisite for the normal progression of male meiosis.

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