Sry was discovered in 1990. Over the following year it was proven to be the Ylinked testis determining gene in both mice and humans through a ombination
of mutation studies and transgenic experiments (Sinclair et al 1990, Gubbay et al 1990, 1992, Berta et al 1990, Koopman et al 1991). At this time, life seemed simple.
Sry was the only gene so far identi¢ed that was known to be involved in diverting the pathway of gonadal development to make a testis rather than an ovary. We also knew two of the factors that e¡ectively exported the male signal to the rest of the developing embryo.