Document Detail

Epithelial cell polarity in early Xenopus development.
MedLine Citation:
PMID:  7626797     Owner:  NLM     Status:  MEDLINE    
The Xenopus blastula consists of two morphologically distinct cell types. Polarized epithelial cells build up the embryonic surface and fence off an inner non-polarized cell population. We examined the establishment of this early functional cell diversification in the embryo by single cell analysis, in vitro cell culture, and transplantation experiments. Single blastomeres from a 64-cell embryo (1/64 cells) exhibit several features of polarized cells. The plasma membrane of 1/64 cells consists of an apical domain, which is inherited from the original egg membrane, and a basolateral domain derived from newly formed membrane during cleavage. These are inherent, cell-autonomous properties of the blastomeres, as they form and are maintained in blastomeres raised in the absence of any cell interactions in calcium free medium. Upon in vitro culture a single 1/64 cell gives rise to an aggregate of two different cell types. Cells carrying a part of the former egg membrane domain differentiate into polarized epithelial cells, whereas cells lacking this membrane domain are not polarized. These results demonstrate that the inclusion of the egg membrane, rather than external signals related to the position of a cell in the intact embryo, is required for the apical/basolateral differentiation of the surface epithelium. This view is supported by cell transplantation studies. A single 1/64 cell was implanted into the blastocoel of a stage 8 blastula embryo. The progeny of the implanted cell proliferate within the host embryo and split into two morphologically distinct populations with different cell behaviours. Cells incorporating a part of the egg membrane form coherent patches of polarized epithelial cell sheets in the interior of the host embryo. In contrast, cells lacking egg membrane do not exhibit any characteristics of polarized cells and eventually spread into different regions of the host embryo. Our results show that the egg membrane and/or components of the submembrane cortex play a determinative role in the formation of the blastula epithelium.
H A Müller; P Hausen
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Developmental dynamics : an official publication of the American Association of Anatomists     Volume:  202     ISSN:  1058-8388     ISO Abbreviation:  Dev. Dyn.     Publication Date:  1995 Apr 
Date Detail:
Created Date:  1995-09-07     Completed Date:  1995-09-07     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  9201927     Medline TA:  Dev Dyn     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  405-20     Citation Subset:  IM    
Max-Planck-Institut für Entwicklungsbiologie, Abteilung Zellbiologie, Tübingen, Federal Republic of Germany.
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MeSH Terms
Blastocyst / cytology
Blastomeres / cytology*,  metabolism,  transplantation
Cell Aggregation
Cell Polarity*
Embryo, Nonmammalian / cytology
Epithelial Cells
Intercellular Junctions / ultrastructure
Microscopy, Electron
Transplantation, Heterotopic
Xenopus laevis / embryology*

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