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largest cell on Earth?

Pflieger Jean-Francois pfliegej at ERE.UMontreal.CA
Sat Feb 22 11:58:14 EST 1997


brians at interlog.com (Brian Scott) writes:
>Pflieger Jean-Francois <pfliegej at ERE.UMontreal.CA> wrote:
>>thedoms at mindspring.com (Marco Domeniconi) writes:
>>>I do not have any ref to confirm the ostrich egg, but I recall having
>>>read somewhere that it is indeed the largest cell.
>>
>>If you consider that spermatozoids (postmeiotic "cells") are true cells, 
>>you could consider that unfertilized ostrich eggs are cells. Fertilized 
>>eggs are "cells" (because dividing rapidly).
>>
>>I think that postmeiotic structures (ova and spermatozoids) could not be 
>>considered as "cells" by comparison with somatic cells, for a given species. 
>>But it's a personal point of view.

>Why not?  They have plasma membranes separating them from their 
>environment.  They have DNA and synthesize mRNA and proteins.  Sperm are 
>even motile like other single-celled organisms.  The yolk of an egg is 
>just very large stores of nutrients etc. contained within intracellular 
>organelles.  They are of course called germ cells.

Yes, but as I state it's a personal point of view. Germ "cells" are very 
different from somatic cells, for a given species. Not only for their 
ploidy, but remind that "mature" sperms synthetize no more proteins (I 
don't remember if mature ova does it, until fertilization at less), and 
that "germ cells differentiation" is very different than somatic cell 
differentiation. But, it's always possible to see germ cells as very 
specialized cells. 

>> >If I remember well, 
>there is an alguae which is visible without 
>>microscopic intrument (ressembling as a small "flower"), but has only one 
>>cytoplasmic compartment and one nucleus... a good large cell no? :-)

>You're probably thinking of Caulerpa which others have mentioned in 
>regards to a Scientific American article (Dec. 1994).  That article does 
>not say Caulerpa is in fact the largest cell.  It does say that Caulerpa 
>is the largest "single-celled organism" though. 

So, I must be wrong. Perhaps, the ostrich egg should be considered as the 
largest cell.

			Jean-Francois

	

-- 
Jean-Francois Pflieger		      "DINANZI A ME NON FUR COSE CREATE,
Universite de Montreal		       SE NON ETERNE ED IO ETERNA DURO:
Sciences Neurologiques		       LASCIATE OGNI SPERANZA, VOI CH'ENTRATE"
pfliegej at alize.ere.umontreal.ca	      (Dante, "l'Enfer, Chant III, vers 7 a 9)



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