Postmeiotic sex chromatin in the male germline of mice

Curr Biol. 2006 Apr 4;16(7):660-7. doi: 10.1016/j.cub.2006.01.066.


In mammals, the X and Y chromosomes are subject to meiotic sex chromosome inactivation (MSCI) during prophase I in the male germline, but their status thereafter is currently unclear. An abundance of X-linked spermatogenesis genes has spawned the view that the X must be active . On the other hand, the idea that the imprinted paternal X of the early embryo may be preinactivated by MSCI suggests that silencing may persist longer . To clarify this issue, we establish a comprehensive X-expression profile during mouse spermatogenesis. Here, we discover that the X and Y occupy a novel compartment in the postmeiotic spermatid and adopt a non-Rabl configuration. We demonstrate that this postmeiotic sex chromatin (PMSC) persists throughout spermiogenesis into mature sperm and exhibits epigenetic similarity to the XY body. In the spermatid, 87% of X-linked genes remain suppressed postmeiotically, while autosomes are largely active. We conclude that chromosome-wide X silencing continues from meiosis to the end of spermiogenesis, and we discuss implications for proposed mechanisms of imprinted X-inactivation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Chromatin / metabolism
  • Chromosome Positioning / physiology*
  • Male
  • Meiosis / physiology*
  • Mice
  • Oligonucleotide Array Sequence Analysis
  • Spermatids / cytology
  • Spermatids / ultrastructure
  • Spermatogenesis*
  • Spermatozoa / ultrastructure*
  • X Chromosome / metabolism*
  • X Chromosome Inactivation / physiology
  • Y Chromosome / metabolism*


  • Chromatin

Associated data

  • GEO/GSE4193