Müller HA (2001), Of mice, frogs and flies: generation of membran...

XB-ART-8659

Dev Growth Differ 2001 Aug 01;434:327-42. doi: 10.1046/j.1440-169x.2001.00587.x.

Show Gene links Show Anatomy links

Of mice, frogs and flies: generation of membrane asymmetries in early development.

Müller HA .

???displayArticle.abstract???
Embryonic development begins with cleavage of the fertilized egg. Cleavage comprises two major processes: cytokinesis and formation of a polarized epithelial cell layer. The focus of this review is comparison of the generation of membrane polarity during embryonic cleavage in three different developmental model systems. In mammalian embryos, as exemplified by analysis of the mouse, generation of distinct membrane domains is uncoupled from cleavage divisions and is initiated in a specific developmental phase, called compaction. In Xenopus laevis embryos, generation of polarized blastomeres occurs simultaneously with cytokinesis. The origin of specific membrane domains of X. laevis polar blastomeres, however, can be traced back to oogenesis. Finally, in Drosophila melanogaster, generation of polarized cells occurs at cellularization. The relevance of cell adhesion, cell junctions and cytocortical scaffolds will be discussed for each of the model systems. Despite enormous morphologic differences, the three models share many common features; in particular, many important molecular interactions are conserved.

???displayArticle.pubmedLink??? 11473540
???displayArticle.link??? Dev Growth Differ

Species referenced: Xenopus laevis
Genes referenced: cdh3 nhs

???attribute.lit??? ???displayArticles.show???

	Fig. 1. Cleavage and membrane polarization in (A) mouse and (B) Xenopus laevis embryos. (A) In the mouse, the first three cleavage divisions occur without a major change in cell surface or membrane polarities. At the 8-cell stage, the embryo undergoes compaction resulting in polarization of the blastomeres and establishment of apical (red) and basolateral (green) membrane domains. (C) The polarized blastomeres undergo symmetric (1) or asymmetric (2) cleavages, giving rise to blastomeres that will either form the polarized trophectoderm epithelium or the non-polarized inner cell mass of the blastocyst (see A, left-hand panel). (B) In X. laevis, the oocyte plasma membrane initially exhibits a character more like the basolateral membrane of polarized epithelial cells. During maturation, the membrane characteristics are converted into a more apical (red) character. Cleavage results in massive insertion of plasma membrane from internal pools, which form the basolateral (green) membrane domains. Like mouse blastomeres, polarized X. laevis blastomeres can undergo either symmetric (C 1) or asymmetric (C 2) cell divisions.

	Fig. 4. Composition of the furrow canal in Xenopus laevis cleavage. Embryos were treated with biotin- X-NHS to label cell surface proteins prior to the first cleavage division. After fixation, biotin moieties were detected by immunolabeling with antibodies directed against biotin (green). (A) Section through the animal pole of a fertilized egg before the first cleavage. The entire plasma membrane is labeled with biotin antibodies. (B) Section through a cleavage stage embryo; animal pole is up. Note strong biotin labeling in the furrow canal, which is marked by the arrow. Arrowheads point to yolk platelets, which exhibit a yellow autofluorescence.