Early inductive interactions are involved in restricting cell fates of mesomeres in sea urchin embryos.

Published

Journal Article

Isolated intact caps of animal blastomeres, obtained from either 8- or 16-cell embryos, differentiate as swollen ectodermal vesicles. These findings agree with earlier studies demonstrating that mesomeres contribute only to larval ectoderm during normal development. In contrast, we find that pairs of mesomeres isolated from 16-cell embryos can differentiate endodermal and mesenchymal cells in a substantial number of cases (23%). Thus, mesomeres have a greater developmental potential than is realized during normal development. Further results support hypotheses that graded distributions of morphogenetic determinants exist within these embryos, since the extent of differentiation of isolated mesomeres is related to the relative position of the third cleavage plane along the animal-vegetal axis. When the third cleavage plane is subequatorial and the resulting animal blastomeres inherit a fraction of the vegetal hemisphere, more cases (39%) differentiate endodermal and mesenchymal cell types. A significant number of mesomere pairs (9-14%), however, can still differentiate endodermal and mesenchymal cells when the mesomeres are formed within the animal hemisphere. Thus, putative vegetal morphogenetic determinants may extend into the animal hemisphere in some cases. Further results indicate a temporal restriction in the developmental potential of mesomeres or mesomere progenitor cells since their differentiative capability is greater if they are isolated earlier during development. Aggregates of isolated mesomere pairs also display a decreased developmental potential when compared to isolated mesomere pairs. These results suggest that associations with adjacent cells (vegetal cells as well as adjacent mesomeres) restrict the development of mesomeres between third and sixth cleavages.

Full Text

Duke Authors

Cited Authors

  • Henry, JJ; Amemiya, S; Wray, GA; Raff, RA

Published Date

  • November 1989

Published In

Volume / Issue

  • 136 / 1

Start / End Page

  • 140 - 153

PubMed ID

  • 2806717

Pubmed Central ID

  • 2806717

Electronic International Standard Serial Number (EISSN)

  • 1095-564X

International Standard Serial Number (ISSN)

  • 0012-1606

Digital Object Identifier (DOI)

  • 10.1016/0012-1606(89)90137-1

Language

  • eng