Figure 3. Waves of Sprr2d and 1700106J16Rik expression in genital ridges.

WISH analysis of Sprr2d (A) and 1700106J16Rik (B) expression in early stage gonads. White arrowheads indicate the anterior and posterior ends of the developing gonads, black arrowheads indicate the anterior and posterior boundaries of gene upregulation, and red arrowheads indicate the anterior and posterior boundaries of gene downregulation. In each panel, the gonad is oriented to the left of the mesonephros. A, anterior; P, posterior. (A) Sprr2d was expressed initially in the central region of XX and XY gonads from 12 tail somite (ts) (~E11.0) stage fetuses, and then expression spread to the anterior and posterior poles at later stages. In XY gonads, there was a region in the center where Sprr2d expression was decreased by the 20 ts (~E11.75) stage. This region of downregulation spread both anteriorly and posteriorly until expression could not be detected in XY gonads at E12.75. In XX gonads, a region of Sprr2d downregulation was consistently detected at the anterior end by E12.75. (B) 1700106J16Rik was initially expressed in the central region of 14 ts (~E11.0) XX and XY gonads and then spread to both the anterior and posterior poles. By the 21 ts (~E11.75) stage, there was a region in the center of XY gonads where 1700106J16Rik expression was decreased. This region of downregulation spread both anteriorly and posteriorly until expression was not detected in XY gonads at the 27 ts (~E12.25) stage.