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Updated: Jan 26, 2026

Preparation of Meiotic Chromosome Spreads from Zebrafish Spermatocytes
Published on: March 3, 2020
Evolution and meiotic organization of heteromorphic sex chromosomes
Tasman Daish1, Frank Grützner1
1Comparative Genome Biology Laboratory, Department of Molecular and Biomedical Science, School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia.
Abstract:
The evolution of heteromorphic sex chromosomes has occurred independently many times in different lineages. The differentiation of sex chromosomes leads to dramatic changes in sequence composition and function and guides the evolutionary trajectory and utilization of genes in pivotal sex determination and reproduction roles. In addition, meiotic recombination and pairing mechanisms are key in orchestrating the resultant impact, retention and maintenance of heteromorphic sex chromosomes, as the resulting exposure of unpaired DNA at meiosis triggers ancient repair and checkpoint pathways. In this review, we summarize the different ways in which sex chromosome systems are organized at meiosis, how pairing is affected, and differences in unpaired DNA responses. We hypothesize that lineage specific differences in meiotic organization is not only a consequence of sex chromosome evolution, but that the establishment of epigenetic changes on sex chromosomes contributes toward their evolutionary conservation.
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