Ureter anlage and metanephric blastema: reciprocal induction
The interaction between the ureter anlage (epithelial tissue) and the metanephric blastema (mesenchyma) is of decisive importance for renal development. The development of the kidneys represents a classical model of a sequential and reciprocal induction between epithelium and mesenchyma. (recall)
For this reason it is frequently used for investigating the molecular cell mechanisms that play a role in the entire organogenesis.
Renal development comprises a whole series of developmental processes such as forming an epithelial tree structure, interactive tissue induction, differentiation, polarization, migration, cell adhesion and finally the epithelio-mesenchymal transformation.
During the genesis of the metanephros, the metanephric blastema first induces the branching of the ureter anlage, which, for its part, then lets the metanephric vesicle form into a predetermined blastema. Through the transformation into epithelial tissue, the renal tubules form and finally the nephrons emerge. The most recent molecular-biologic research, mainly on transgenic mice, has shown that several factors are involved in this process. These various factors can be gone into only briefly in this chapter; those wishing to dig deeper can have a look at the cited references.