Mesonephric Wnt Signaling Associate with a Formation of an Adreno‐Gonadal Primordium in Chick Embryos

Abstract

The adrenal cortex as well as the reproductive tract, kidney, and gonad is derived from the intermediate mesoderm. In addition, the mesonephros essential for the early adrenal development also originates from the intermediate mesoderm. A contribution of mesonephros to adrenal formation through expression of growth factors has been largely unknown. Moreover, Ad4 binding protein/steroidogenic factor 1[Ad4BP/SF-1(NR5A1)], and Dmrt-1(doublesex- and mab-3-related transcription factor) are expressed in adrenal and gonadal development chick embryos. What growth factor(s) regulate the expression of Ad4BP/SF-1 and Dmrt-1, has not been determined. Here we show with chick embryos that Wnt4 is expressed in only certain parts of the mesonephric tubules, while the expression was also detected in the mesenchyme at stage 21. Moreover, Ad4BP/SF-1 and Dmrt-1 were expressed in the developing adreno-gonadal and gonadal primordial at the same stage adjacent to the expressions of Wnt4. To examine the possibility that Ad4BP/ SF-1 and Dmrt-1 were influenced by Wnt4, we performed with misexpression. Our studies showed that Wnt4 expanded marker gene expression for the adreno-gonadal primordium, whereas Wnt4 does not stimulated gonad formation. We conclude that Wnt signaling is involved in the formation of the adreno-gonadal primordium.