Reconstruction of bipinnaria larvae from dissociated embryonic cells of the starfish, Asterina pectinifera.

Cells dissociated from swimming embryos of the starfish are able to reconstruct bipinnaria larvae. This process consists of reaggregation (stage 1), formation of the external epithelium (stage 2), development of the internal cavities which will eventually grow either into the blastocoel or the intestinal lumen (stage 3), gastrulation or fusion of the internal and the external epithelia (stage 4), formation of the mouth (stage 5) and the established bipinnaria (stage 6). The optimal population of cells to support the process of reconstruction is estimated to fall between 500 and 1000, values corresponding to one eighth and one fourth the total number of cells of a normal embryo, respectively. Morphogenetic events of reconstruction are discussed in relation to the normal course of starfish development and to the reconstruction process of the sea urchin.