Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published July 1997 | public
Journal Article

Set-aside cells in maximal indirect development: evolutionary and developmental significance

Abstract

In the maximal form of indirect development found in many taxa of marine invertebrates, embryonic cell lineages of fixed fate and limited division capacity give rise to the larval structures. The adult arises from set-aside cells in the larva that are held out from the early embryonic specification processes, and that retain extensive proliferative capacity. We review the locations and fates of set-aside cells in two protostomes, a lophophorate and a deuterostome. The distinct adult body plans of many phyla develop from homologous set-aside cells within homologous larvae. We argue that the stocks from which these phyla arose utilized these respective larvae, and the diversity of their adult body plans reflects diverse pattern formation processes executed in their set-aside cell populations. Chordates and arthropods develop directly, but share adult characters with indirectly developing phyla. Thus the deuterostome and protostome stocks that were ancestral to chordates and arthropods, respectively, also utilized maximal indirect development.

Additional Information

© 1997 ICSU Press. Accepted 12 March 1997. We are much indebted to our colleagues for their extremely helpful insights and discussion of the ideas in this essay: Dr Andrew Ransick and Prof. Ellen Rothenberg, both of Caltech. We also wish to extend our gratitude to two extremely helpful anonymous referees, and to Dr Adam Wilkins, Editor of BioEssays, for his detailed comments as well. This work was supported by a grant from the National Institute of Child Health and Human Development (HD05753).

Additional details

Created:
August 19, 2023
Modified:
October 19, 2023