Send to:

Choose Destination
See comment in PubMed Commons below
Gravit Space Biol Bull. 1998 May;11(2):15-21.

Blastopore formation in the animal hemisphere: functional inversion of gastrulation by centrifugation of Xenopus laevis eggs.

Author information

  • 1Department of Biology, Reed College, Portland, Oregon, USA.


Eggs of Xenopus laevis and many other amphibians contain a gradient of yolk platelets along the animal-vegetal axis. Small platelets predominate in the animal hemisphere, and a boundary between medium and large yolk platelets exists near the equator. The blastopore forms at this boundary at the beginning of gastrulation, in the vegetal hemisphere. Does this boundary have a role in determination of the position of the blastopore, or does cortical information predominate? Past experiments using 1g to invert the egg showed a distinct tendency to form the blastopore in the original vegetal hemisphere. Our experiments, however, have used 20g centrifugation to achieve a more complete inversion of the yolk gradient. The blastopore formed in the original animal hemisphere in >95% of surviving gastrulae, if centrifugation was begun at normalized time 0.20-0.25 of the first cell cycle. Nearly normal larvae (DAI grades 4 and 5) form in 64% of cases (ave. DAI = 3.2). These data support the idea that the position of the blastopore depends on the position of the egg's internal contents rather than cortical determinants.

[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Loading ...
    Write to the Help Desk