Spatially dynamic expression of Sry in mouse genital ridges

We have studied the spatial dynamics of Sry transcription in the genital ri dges of mouse embryos. We find that Sry is expressed in a dynamic wave that emanates from the central and/or anterior regions, extends subsequently to both poles, and ends in the caudal pole. This dynamism may explain the rel ative positioning of ovarian and testicular tissue seen in ovotestes in mic e. Since direct regulatory targets of SRY ought to be expressed in a corres ponding or complimentary wave, our observations pave the way for identifica tion of target genes. Sry is expressed in internal cells but not in coelomi c surface epithelial cells, indicating that its effect on proliferation of surface cells is achieved non-cell-autonomously. The cellular dynamism of S ry expression revealed in this study thus provides important insights into both the cellular and molecular mode of action of SRY, and how perturbation s in Sry expression can lead to anomalies of sexual development. (C) 2001 W iley-Liss, Inc.