In article <Pine.OSF.3.95.970129180308.16613E-100000 at pipe11.orchestra.cse.unsw.EDU.AU>,
Van Dung Ly <vanly at cse.unsw.EDU.AU> wrote:
>My Question:
>When a mammalian female's egg gets fertilized by a sperm and cell division
>takes place, do we know how cells come to know where they are (relative
>to each other) so that some become eg. kidney cells, brain cells, muscle
>cells, nerve cells etc. ?
Not in great detail, no. Several of the basic principles are
understood, especially in other organisms. Mammalian development is
difficult to work with experimentally for obvious reasons (it occurs
inside the mother). Most research into developmental mechanisms
is done on other organisms: Drosophila (a fruit fly), Xenopus (a
frog), zebrafish and chickens. Of these, drosophila is probably the
easiest for you to start with. The initial laying down of the
segmentation pattern, the definition of which end is which and
which side is the back and which is the front is really elegant.
Later on these basic definitions are used like grid references on a
map so that a cell knows where it is (for example, if the
concentration of a protein called 'bicoid' is quite high, the cell
will 'know' that it is quite near the head end of the embryo).
A classic book on development is this, if you want to read further:
Author: Wolpert, L. (Lewis)
Title: The triumph of the embryo/ Lewis Wolpert; with
illustrations drawn by Debra Skinner
Oxford; New York: Oxford University Press, 1993
vii,211p; 24cm (pbk)
Tim.
