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

Infection - complications of cardiac surgery, Infection Due to the m...

Infection Due to the many invasive monitoring techniques, ET tube, urinary catheter, surgical interventions. Cultures of blood or sputum/urine/swab form the wound is don

Is glucose can be oxidized to two primary products, In the RBC, glucose can...

In the RBC, glucose can be oxidized to two primary products. One of the oxidation proucts is ribulose 5 phosphate, and the other is which of the following compounds? -lactate

Illustrate the plant taxonomy, Q. Illustrate the Plant taxonomy? Plant ...

Q. Illustrate the Plant taxonomy? Plant taxonomy has a long history. It gave birth to several phases of botany but remains exciting, interesting and important because there is

Describe the biological parameters of living organisms, Describe the Biolog...

Describe the Biological parameters of living organisms Biological parameters which include living organisms constitute an important component of soil.  Even though organisms fo

Organic Evolution, I am studying the evolution of a giraffe. How do I find ...

I am studying the evolution of a giraffe. How do I find more information?

In what form is most carbohydrate taken in the normal diet, In what form is...

In what form is most carbohydrate taken in the normal diet? Most carbohydrate is taken normal diet in as starch.

What is physiology and hemodynamic, What is Physiology and Hemodynamic ? ...

What is Physiology and Hemodynamic ? Normally, in the post-natal circulation the pulmonary and aortic circuits are in series so that the deoxygenated blood coming into the righ

Children with infective endocarditis, Among neonates, IE typically involves...

Among neonates, IE typically involves the tricuspid valve of structurally normal hearts and is associated with very high mortality rates.  It is likely that many of these episodes

Diversity2, using examples of invertebrate phyla illustrate how the increas...

using examples of invertebrate phyla illustrate how the increase in complexity is reflected by their nervous system?

Define about the simple proteins, Define about the Simple proteins? Sim...

Define about the Simple proteins? Simple proteins are those which contain only amino acids or their derivatives and no prosthetic group. They yield only amino acids or their de

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