Fig. 1From: A primer on the use of mouse models for identifying direct sex chromosome effects that cause sex differences in non-gonadal tissuesMajor parts of the mouse X and Y chromosomes. Top: The 170-Mb X chromosome is divided into the pseudoautosomal region (PAR), containing the Sts gene and a few others, and the non-PAR region (NPX). The 89-Mb Y chromosome comprises the PAR and non-PAR Y (NPY). The Sry gene is on the Y chromosome short arm. Bottom: XX progeny inherit X chromosomes from the mother (Xm) and father (Xp). The XX mouse is a mosaic of cells expressing one of the parental X chromosomes. Green shows the patches of tissues in which Xp is active, and lavender shows the patches in which Xm is active. The XY mouse inherits the Xm and expresses only that X chromosome in all tissues. CEN centromereBack to article page