Determination of the mesonephric kidney

The determination of the mesonephric kidney in Taricha torosa involves both inductive and suppressive interactions between the kidney mesoderm and other embryonic tissues. The analysis of kidney determination was made by explanting the mesonephrogenic mesenchyme in epidermal vesicles either alone or in combination with the endoderm, notochord, neural tube, neural crest, lateral plate mesoderm, somite or nephric duct. It was found that the endoderm, notochord, early somite, and early lateral plate mesoderm are inductors of the mesonephros. Also, both premigratory and migratory neural crest cells, neural tube, older somite, and older lateral plate mesoderm were identified as suppressors of the development of the mesonephros. Most of the above interactions occur before the nephric duct makes contact with the mesonephrogenic mesenchyme. Too much emphasis has been placed on the nephric duct as being the inductor of the mesonephros. The mesonephric kidney is determined by late tailbud stages; a result of the inductive and suppressive interactions it has experienced.