This research was supported by grants from the National Science Foundation.
Early events in sea urchin metamorphosis, description and analysis†
Article first published online: 6 FEB 2005
Copyright © 1978 Wiley-Liss, Inc.
Journal of Morphology
Volume 157, Issue 1, pages 21–31, July 1978
How to Cite
Cameron, R. A. and Hinegardner, R. T. (1978), Early events in sea urchin metamorphosis, description and analysis. J. Morphol., 157: 21–31. doi: 10.1002/jmor.1051570103
- Issue published online: 6 FEB 2005
- Article first published online: 6 FEB 2005
The larval epithelium of the sea urchin, Lytechinus pictus, consists of squamous cells and bands of columnar epithelial cells bearing cilia. During metamorphosis this tissue undergoes a series of rapid, complex changes. Through the scanning and transmission electron microscope, we describe and analyse these changes. The changes can be divided into three steps. (1) The larval arms bend away from the left side of the larva, exposing the urchin rudiment. Cells which are identical to smooth muscle cells are in a position to bring about this bending. (2) The squamous epithelial cells assume a cuboidal shape. This change in shape results in the collapse of the larval epithelium onto the presumptive aboral surface. These cells possess a subapical band of microfilaments. The cellular shape change but not the bending of the arms is reversibly inhibited by Cytochalasin B. These observations suggest a mechanism for this change. (3) The former lining of the vestibule of the urchin rudiment comes to lie over the collapsed larval tissue and forms the adult epithelium. At this point, after only one hour, the larva has assumed the external shape of an adult sea urchin.