Plea for explanation!

Dennis Goode dg0 at UMAIL.UMD.EDU
Wed Sep 30 10:41:41 EST 1998


On Wed, 30 Sep 1998 10:32:53 +0200 Martin Ortseifer 
<ortseife at mpip-mainz.mpg.de> wrote:


> in my studies of cellbiologie, exactly mitosis, I am confronted with two
> terms, to which I haven't yet seen any definition or explanation. So,
> what is meant by:
> 
> 		Amitosis
> 		Endomitosis
> 
Martin,

Amitosis is the division of a eukaryotic nucleus in two 
or more parts without the formation of a metaphase plate or 
typical mitotic apparatus. An example is the division of 
the ciliate macronucleus, which although it involves 
Microtubules, is not mitosis (see Walker and Goode 
Cytobiologie14:18-37).
The micronucleus in the same cells divide mitotically, with 
microtubules attaching to kinetochores and going thru 
metaphase and anaphase.

Endomitosis, on the other hand, is the duplication of the 
chromosomes within the nucleus, but no nuclear division 
occurs, thus the number of chromosomes per nucleus doubles.
They go thru prophase but no MA forms and no metaphase, 
anaphase or telophase. See Dan Mazia's wonderful "chapter" 
in The Cell, Vol 3.
 
-Dennis

----------------------
Dennis Goode 
Dept. of Biology
University of Maryland
College Park 20742
dg0 at umail.umd.edu




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