title: The role of X-chromosome inactivation during spermatogenesis (Drosophila-allocycly-chromosome evolution-male sterility-dosage compensation).
abstract: Inactivation of the single X chromosome in the primary spermatocytes of species with heterogametic males is postulated as a basic control mechanism on the chromosomal level that is required for normal spermatogenesis. This view is supported by (a) cytological observations of X-chromosome allocycly in the primary spermatocytes of all male-heterogametic organisms that were adequately examined, (b) autoradiographic evidence of early cessation of transcription by the X chromosome in the mouse and three species of grasshopper, and (c) the male sterility of animals with certain X-chromosome rearrangements that cannot be attributed to misfunction of specific genes. X-chromosome inactivation during spermatogenesis is proposed as the ideal system for studies of genetic control at the chromosomal level.
mesh_terms: D000818:Animals; D002869:Chromosome Aberrations; D004331:Drosophila melanogaster; D006110:Grasshoppers; D007248:Infertility, Male; D008297:Male; D008540:Meiosis; D051379:Mice; D009154:Mutation; D012730:Sex Chromosomes / Q000502:physiology*; D013091:Spermatogenesis; D013094:Spermatozoa / Q000502:physiology*