Re: Structuralism and evolutionary theory

From: Dr. David Campbell <>
Date: Tue Nov 01 2005 - 13:45:56 EST

> Frustratingly enough, I can recall but not locate a recent article
> that said that a detailed analysis of the cells after a very few
> divisions (during the twin-possibility stage) showed that the
> division of cellular contents were not exactly identical among the
> cells.

Twin-possibility stage applies only to a few phyla. Most animals have
clear differentiation of cells very early in development, with no
chance of twins. This includes such popular lab animals as nematodes
and insects. The uneven distribution of activity in or product of
many genes from the start of development is known; in turn these
affect other genes.

Dr. David Campbell
425 Scientific Collections Building
Department of Biological Sciences
Biodiversity and Systematics
University of Alabama, Box 870345
Tuscaloosa AL 35487-0345  USA
Received on Tue Nov 1 13:47:43 2005

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