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

Conformational protection - azotobacter, Conformational Protection - Azotob...

Conformational Protection - Azotobacter In conformational protection a Fe-S redox protein provides protection to the enzyme. The protein gets oxidised in the presence of oxyge

Causes of heart failure, It is important to recognise underlying causes and...

It is important to recognise underlying causes and precipitating factors of heart failure for its appropriate management. That would also help in prevention and treatment of heart

Which is better to grow plants in rock sand or soil, Which is better to gro...

Which is better to grow plants in Rock sand or soil? When we grew plants inside, with there is no wind, and the plants in the rocks grew improved than the plants that were grow

How does the body defend itself from microorganisms, Q. How does the body d...

Q. How does the body defend itself from microorganisms and other harmful substances that enter the airway during the breathing process? The epithelium of the airway is a ciliat

Meiosis comprises two separate divisions, All of the following make meiosis...

All of the following make meiosis different from mitosis; EXCEPT A. Meiosis comprises two separate divisions. B. Meiosis only occurs during embryonic development. C. Chromoso

Hassan, function of epithelial tissue

function of epithelial tissue

Human evolution, In the last unit we traced the human evolutionary history ...

In the last unit we traced the human evolutionary history mostly from a palaeontological viewpoint. Although still fragmentary, the available fossil evidence makes it possible to c

Ablation experiment, Ablation experiment  is an experiment designed to prod...

Ablation experiment  is an experiment designed to produce an animal deficient in one or the few cell types, in order to study cell lineage or the cell function. The logic is to mak

Walrasian model, Normal 0 false false false EN-IN X-N...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Anterior interventricular - artery, The arterial supply is  by the right an...

The arterial supply is  by the right and left coronary arteries. In the event of sudden block of one artery the area of myocardium supplied by that artery undergoes infarction.

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