Embryonic Similarity

Embryonic Similarity

 

the similarity of the embryos of animals of distant taxonomic groups, such as in vertebrates (in the stages of gastrulation, formation of the germ layers, organogenesis) and in arthropods.

Embryonic similarity was first described by K. M. Baer in 1828. As C. Darwin showed in 1859, embryonic similarity is a consequence of the commonality of animal origin. According to the theory of phylembryogenesis proposed by A. N. Severtsov, embryonic similarity is the result of evolution that proceeds predominantly by means of anabolism, that is, by supplementation and extension of the final stages of ontogeny. Mutations, unless they cause nonviability of the organism, do not affect the initial stages of embryonic development, and manifest themselves only at the end of morphogenesis. Thus, embryonic similarity is the result of the strict correlatedness and conservatism of the processes that occur in the early stages of ontogeny.

E. N. MIRZOIAN

References in periodicals archive ?
Developmental biologists, however, have often favored von Baer's (1828) careful statements on embryonic similarity and subsequent divergence (which did not necessarily imply evolutionary meaning) over Haeckel's bolder conception (cf.