What is oogenesis , Biology

Assignment Help:

What is Oogenesis ?

The female sex cells, or eggs, are formed in the ovaries, the primary sex organs of the female. The precursor of the egg cells, or oogonia, are formed during the prenatal development of the ovaries in the female embryo. However, the oogonia do not increase in number until after the third month of fetal development.

Oogonia divide by mitosis to form primary oocytes. These cells gradually die off, but about 200,000 are left in each ovary at puberty (about 11 to 14 years of age). Over the course of a woman's reproductive life, only about 450 oocytes will mature completely into eggs.

The primary oocyte begins meiosis, undergoing a very unequal division in which the larger cell becomes a secondary oocyte, and the other forms the first polar body, which eventually dies off. The second meiotic division, also unequal, forms a haploid ootid and a second polar body that also dies off. What is left is a single haploid egg cell or ovum (plural ova) that is 75,000 times larger than a sperm cell. The ovum contains contains proteins, lipids, and other raw materials for development. It is thought that the reason 3 of the 4 cells that result from meiosis die off is to provide the one surviving egg with sufficient resources for development.

 


Related Discussions:- What is oogenesis

State in brief about posterior maxilla, Posterior Maxilla Posterior max...

Posterior Maxilla Posterior maxilla has very poor quality of bone demanding special consideration in implant placement:  Increasing the number of implants to decrease the cr

Explain curdlan, Curdlan Curdlan, a glucan with (1→3) is produced by ba...

Curdlan Curdlan, a glucan with (1→3) is produced by bacterium  Alkaliqenus faecalis  var. myogenes and some related bacteria. It is a tasteless, odorless white powder, which sw

Illustrate dark reactions, Q. Why is the nickname "dark reactions" not comp...

Q. Why is the nickname "dark reactions" not completely correct for the chemical stage of photosynthesis? "Dark reactions" is not a correct name for the chemical phase of photos

Determine the modification of native starch, Determine the Modification of ...

Determine the Modification of native starch Modification of native starch can be either physical or chemical. Chemical modification includes reaction of starch with  acid or al

Describe the parathyroid hormone, A new drug named ANTAG-CaSR has been deve...

A new drug named ANTAG-CaSR has been developed that is an antagonist at calcium-binding sites of CaSRs (Calcium-Sensing Receptors) in the plasma membranes of parathyroid gland cell

What is leaf cuticle, What is leaf cuticle? Leaf cuticle is a thin waxy...

What is leaf cuticle? Leaf cuticle is a thin waxy layer made of waxes and cutin on the outer surface of the leaf epidermis. Its function is near control the cellular transpirat

Explain clinical stigmata of syndromes in heart disease, Explain Clinical s...

Explain Clinical stigmata of specific syndromes in heart disease? Clinical stigmata of specific syndromes: Evidence of preseilce of chromosoinal anomalies or other syndromes

Explain soybean protein, Explain soybean protein The need for the devel...

Explain soybean protein The need for the development of soybean protein concentrates stemmed primarily from two considerations: to enhance protein concentration and to improve

Explain hyperthermophilic organisms, Some hyperthermophilic organisms that ...

Some hyperthermophilic organisms that grow in highly acidic (pH2) habitats belong to the two groups: 1. Eubacteria and archaea 2. Cyanobacteria and diatoms 3. Protists and

Define reaction of fehling solution with lactose, Define Reaction of Fehlin...

Define Reaction of Fehling solution with lactose? After complete reduction of cupric ions, the indicator is reduced by lactose to a leuco compound, restoring the red colour of

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd