In article <pfliegej.856362715 at alize.ERE.UMontreal.CA>,
Pflieger Jean-Francois <pfliegej at ERE.UMontreal.CA> wrote:
>thedoms at mindspring.com (Marco Domeniconi) writes:
>>lance at neuro.pharmacology.ubc.ca (Lance Corey) wrote:
>>>brians at interlog.com (Brian Scott) wrote:
>>>>Andrew Doherty <A.Doherty at Bris.ac.uk> wrote:
>>>>>> >long. Is the ostrich's egg really a single cell?!
>>>>>> Sure it is...isn't it? I mean, it's an ovum and if it's fertilized
>>>>>> it starts dividing right? Help me out here people! :-)
>>>I do not think it is correct to state that the ostrich egg is not a
>>single, large cell based on its high contents of nutrients reserves
>>and fats (up to 95%). If such param for the identification of a "true"
>>single cell was correct, then it would also exclude our own adipose
>>cells, among the largest in our bodies.
>>>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.
> >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. If Caulerpa grew to be
as large as my thumb, it might still be the largest single-celled
organism but be smaller than an ostrich egg. The article does not say
how large individual Caulerpa are. They may exist in the ocean in
colonies of hundreds or thousands of individuals spanning a wide area,
but each individual might be smaller in volume than an ostrich egg. Does
anyone know of any published data on the size of individual Caulerpa?
This thread might be dragging on, but at least I've learned something.
That article on Caulerpa was very interesting. Thanks to those who
pointed it out.
Brian Scott | "In other studies you go as far as others have gone
brians at interlog.com | before you, and there is nothing more to know; but
M.Sc. student in | in scientific pursuit there is continual food for
Neurophysiology | discovery and wonder." - Victor Frankenstein