Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!husc6!linus!philabs!aecom!werner
From: werner@aecom.UUCP
Newsgroups: sci.bio
Subject: Re: Human Asymmetry
Message-ID: <1024@aecom.UUCP>
Date: Fri, 10-Apr-87 17:32:26 EST
Article-I.D.: aecom.1024
Posted: Fri Apr 10 17:32:26 1987
Date-Received: Sat, 11-Apr-87 23:52:18 EST
References: <633@batcomputer.tn.cornell.edu>
Distribution: sci
Organization: Albert Einstein Coll. of Med., NY
Lines: 22


	Anyone wishing to know the ins and outs of biological rotations
during development would be wise to read a book on Embryology.  I
recommend the one by Moore.

	Besides the fact that nature generally only uses one enantiomer
over another, any questions of WHY one was chosen over the other can
be explained down to finer details (cilia, the microtubules that make
up cilia, the tubulin and dynein that makes up microtubules), but 
eventually one gets to the point where one just has to conclude: well,
it had to pick one.

	As for right versus left. It is known that the first cell division
from the egg is non-symettrical nor the second.  From the 4 cell stage
stage, there is already an putative top and an putative front.  Topologists
can verify that means that right and left are constrained.

-- 
			      Craig Werner (MD/PhD '91)
				!philabs!aecom!werner
              (1935-14E Eastchester Rd., Bronx NY 10461, 212-931-2517)
                        "It doesn't even have to be a Pelvis."