MadSci Network: Development
Query:

Re: what is the advantage of unequal cytoplasmic division during oogenesis.

Date: Fri May 14 14:25:47 2004
Posted By: Abhishek Dey Das, Undergraduate, Biology, Bholananda National Vidyalaya
Area of science: Development
ID: 1079479256.Dv
Message:

Gametogenesis is the production of haploid gametes by diploid multicellular
organisms through the process of meiosis. The production of female gametes
or ova (eggs) is called oogenesis. The production of male gametes or
spermatozoa (sperm) is called spermatogenesis. Oogenesis occurs within the
follicles of the ovaries. The meiosis of oocytes always results in halpoid
cells of unequal size. When a primary oocyte undergoes meiosis, a large
halpoid secondary oocyte and a very small first polar body result. A second
meiotic division produces a large ootid and a very small second polar body.
The first polar body may or may not divide during the second meiotic
division into two additional second polar bodies. All the polar bodies are
non-functional. After meiosis, the ootid quickly differentiates into the
mature egg cell or ovum. The unequal cytokinesis that occurs has the
advantage of providing the ovum with a much greater amount of cytoplasm and
stored food than if an equal division were to occur. Thus, the non-motile
ovum supplies a developing embryo with most of its cytoplasm and food while
the much smaller but highly-motile sperm contributes mainly genetic
material to the embryo.

Hope this helps.

-Abhishek Dey Das.
Bholananda National Vidyalaya, Barrackpore.


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