Dynamic patterns of gene expression in the developing pronephros of Xenopus laevis

Data from gene ablation studies in mice have indicated critical roles for l im-1, Wnt4, WT-1, and Pax-2 in the coordination and execution of kidney pat terning and differentiation. However, the precise roles of these molecules, their ordering within a genetic hierarchy, and the manner in which they co ntribute to establishing the fates of cells of each of the components of th e nephron have yet to be elucidated in any system. In this report, the temp oral and spatial expression patterns of these genes within the Xenopus pron ephric system were examined in detail by single-and double-probe in situ hy bridization. We describe restrictions of these gene expression patterns wit hin the pronephros which indicate a model for the partitioning of the commo n pronephric anlage into its three component parts - the tubules, the glomu s, and the dyer. (C) 1999 Wiley-Liss, inc.