Hereditary and induced modifications of the normal necrotic patterns in the developing limb buds of the rat and mouse: facts and hypotheses

Abstract

Similar patterns of physiological cell death appearing according to a precise and predictable schedule can be observed in the developing limb buds of mouse and rat embryos in relation to well defined regional features of limb morphogenesis. They characterize either the apical ectodermal ridge or delineated areas of the undifferentiated mesoderm. Four kinds of modified necrotic patterns have been demonstrated in relation to the genesis of different limb malformations: the absence of cell death in particular areas which are normally affected, excessive cell death occurring on schedule in normal sites, advanced, prolonged or delayed cell necrosis in normal sites, and abnormal cell degeneration unrelated to the normal necrotic pattern. With the exception of the latter category which is more specifically related to chemically induced limb malformations, the first three categories characterize both hereditary and provoked teratological situations.