Sex-determining region SRY on the Y chromosome

The relevant region in man lies in the distal
short arm of the Y chromosome at Yp11.32. The
short arm and the proximal half of the long arm
of the Y chromosome have been divided into
seven intervals (2). The most distal region of the
short arm is the pseudoautosomal region 1 (PAR
1). This region is homologous to the distal segment
of the short arm of the X chromosome.
Homologous pairing occurs here with crossingover
during meiosis. The physical map of the
pseudoautosomal region and the proximal half
of interval 1 (1A1–1B) span somewhat more
than 2500 kb in man (3). Intervals 2–7 contain
no genes for male sex determination. The crucial
portion of the Y chromosome for male sex
determination in man is about 35 kb (in the
mouse about 14 kb) of a region designated Sry
(sex-related Y chromosomal region)