The expression pattern of a mouse doublsex-related gene is consistent witha role in gonadal differentiation

The signal for somatic sex determination in mammals, Caenorhabditis elegans and Drosophila melangogaster is chromosomal, but the overall mechanisms do not appear to be conserved between the phyla. However it has been found qu ite recently that the C. elegans sex-determining gene Mab-3 contains a doma in highly homologous to the Drosophila sex-determining gene doublesex (dsx) and shares a similar role. These data suggest that at least some aspects o f the regulation of sex determination might be conserved. In humans, a doub lesex-related gene (DMRT1) was identified at less than 30 kb from the criti cal region for sex reversal on chromosome 9p24 (TD9). In order to get insig hts into the role of DMRT1 in sex determination/differentiation, we have is olated DMRT1 mouse homologue (Dmrt1) and analysed its expression pattern. T he gene is expressed in the genital ridges of both sexes during the sex-det ermining switch and it shows male/female dimorphism at late stages of sex d ifferentiation. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.