Staging of Embryonic and Larval Amphibians

Abstract

The ontogenetic development of amphibians from the fertilized egg to the completion of metamorphosis has been widely investigated. Details of the topography, anatomy, and histology of the various organs and tissues are now available in the literature, most of them examined in lesser or greater detail to the level of electronmicroscopy. Analyses of ontogeny have also been made at the gross visual level, for a variety of reasons (vide infra), and like a series of photographic stills, successive stages of development of individual species have been arbitrarily tabularized and numbered, though various authors frequently have included the specific levels of internal anatomical development that have occurred in the referred stages. Any examination of the gross external features of amphibian ontogenetic change during development clearly is relevant to a study of morphogenesis especially in anurans; indeed such changes provide a working basis for more detailed research in this field. The following account, therefore, deals with the subject of staging in some detail, but of more importance, it brings up-to-date and lists the relevant publications in the field.