IUBio Biosequences .. Software .. Molbio soft .. Network News .. FTP

largest cell on Earth?

Richard Hall rhall at uvi.edu
Wed Feb 19 12:39:48 EST 1997


What seemes to be the problem here?

If the egg is fertilized, it is no longer a single cell.  If it is not
fertilized, it is likely a single cell in an arrested meiotic state closer
to 3N than 1N. If ploidy is an issue, remember that through alternation of
generations some large plants are 1N.  The ova is initially very small, but
as it passes through the oviduct, the hen invests the egg with lipids and
ovalbumin...a gift for her precocious offspring. Eventually the growing orb
is invested with a connective epithelium that is calcified.  Perhaps that
membrane is cellular or acellular, but it is outside the cell.

Please recall that during the development of the chick embryo that cell
division does not include the entire cell, it is discoidal, due to the
asymmetrical deposition of nutrients in yolk and ovalbumin.  The
extraembryonic tissues that contribute to the yolk sac and the chorion grow
over the rich nutrient stores and begin to mine the riches below.

The giant corticospinal nerve of a blue whale is likely invested with glial
cells, but that does not diminish the size of the pyramidal cell or its
axon.

As to the fungus that has become Michigan, it is one individual, not a
single cell.

rlh


>In article <330a676e.37903907 at news.ucs.ubc.ca>,
>Lance Corey <lance at neuro.pharmacology.ubc.ca> wrote:
>>brians at interlog.com (Brian Scott) wrote:
>>
>>>In article <33096943.1CD7 at Bris.ac.uk>,
>>>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!  :-)
>>>>>
>>>>> Brian
>>>>>
>>>>Well, I'm not so sure an ostrich egg, as such, is a single cell. Surely
>>>>the ostrich ovem is the cell, which becomes the egg i.e. produces the
>>>>shell, yolk sac, albumin...etc. So the ostrich egg may only contain one
>>>>cell, but is not itself that cell - I think - sort of - d'ya get what I
>>>>mean? I'm not sure I do, but then I'm not an ostrich biologist!!!
>>>
>>>
>>>According to _Molecular Biolog of the Cell_ by Alberts et al.,  bird's
>>>eggs are single cells.
>>
>>IMHO, I don't blieve that the whole egg is one cell; more likely, it is a
>>cell surrounded by yolk and albumen.
>>
>>Lance Corey
>>       lance at neuro.pharmacology.ubc.ca
>
>
>I guess it depends on your definition of a cell.  Alberts et al. say that
>the yolk is contained within an organelle -- yolk granules -- within the
>cell's cytoplasm.  They don't say the ovum is a cell associated with an
>external yolk-containing body.
>
>Brian
>
>
>
>--
>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

Richard Hall
Comparative Animal Physiologist
Division of Sciences and Mathematics
University of the Virgin Islands
St. Thomas, USVI  00802

809-693-1386
rhall at uvi.edu





More information about the Neur-sci mailing list

Send comments to us at biosci-help [At] net.bio.net