The mouse pseudoautosomal region (PAR). (A) A physical map of the PAR of laboratory mice (129Sv) incorporating a previously reported study (Kipling et al. 1996a) as well as results presented here. The location of the Fxy gene is indicated by a gray line. PAB indicates the position of the pseudoautosomal boundary; TEL,of the telomere. The presence of two repeat units containing the 3′ ofFxy, DXYMov15, PAR-4, and the interstitial telomeric repeat (TTAGGG)_n are also indicated. The positions of a PacI site and the Steroid sulphatase(Sts) gene have been taken from a study by Kipling et al. (1996a). (B) Schematic of the genomic organization of theFxy gene in laboratory mice. Exons are indicated by gray boxes. The first three exons are X unique, whereas the remaining exons are pseudoautosomal. Intron sizes, where known, are indicated (kb). PAB indicates the position of the pseudoautosomal boundary.