title: Cytological evidence that the Sxr fragment of XY,Sxr mice pairs homologously at meiotic prophase with the proximal testis-determining region.
abstract: Self-pairing of the Y chromosome at prophase of meiosis in XY,Sxr male mice appears to take place in many cells to the exclusion of pairing between the Y and the X. This phenomenon offers an explanation for the high level of X-Y separation seen in these males at prophase of meiosis, additional separations being evident, however, when metaphase I (MI) cells are examined. A minority of prophase cells show the Y paired both autologously and with a sub-terminal region of the X which could be the normal pairing region. The balloon-like configurations observed when self-pairing occurs suggest that the distal Sxr fragment is inverted on the Y chromosome of Sxr carrier males in relation to the normal proximal testis-determining (Td)-containing region.
mesh_terms: D000818:Animals; D012734:Disorders of Sex Development; D008297:Male; D008540:Meiosis; D051379:Mice; D011418:Prophase; D013737:Testis / Q000166:cytology*; D014960:X Chromosome / Q000648:ultrastructure*; D014998:Y Chromosome / Q000648:ultrastructure*