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

Explain class adverse effects of nnrti, Class adverse effects of NNRTI ...

Class adverse effects of NNRTI All NNRTIs can cause a rash that is sometimes severe. NNRTIs are metabolized by and can affect hepatic CYP 450 isozymes; drug interactions can o

Functions of plasma proteins, Functions of Plasma Proteins The protein...

Functions of Plasma Proteins The proteins of the plasma serve several important functions. They exert osmotic pressure varying from 25 to 30 mm Hg, which regulate

Hypospadias, Hypospadias Hypospadias is the most common congenital an...

Hypospadias Hypospadias is the most common congenital anomaly of the penis. In this uretheral opening is situated on ventral side of the shaft of penis in one or several posi

Explain the predator-prey relationships, Explain the Predator-Prey Relation...

Explain the Predator-Prey Relationships ? The feeding by a population of one species upon members of another species is referred to as predation. Many scientists also consider

What is test battery, What is test battery A series of tests (called a ...

What is test battery A series of tests (called a test battery) will be given. One widely used battery is Halstead Reitan, which includes measures of verbal and nonverbal intell

Ethylene production - responses to infection, Ethylene production - Res...

Ethylene production - Responses to Infection Ethylene is also induced in response to infection. It is also known to be produced under other stress conditions like wounding

What do you know zoological parks, Q. What do you know Zoological Parks? ...

Q. What do you know Zoological Parks? Zoological park has two faced aspects, the relationship between man and beast. There is awe and there is slaughter. There is worship and t

How are secondary cell walls different from primary cell, How are secondary...

How are secondary cell walls different from primary cell walls? Primary cell walls are assembled on the surface of the plasma membrane whereas the cell is growing. They can gro

Show the process by which the neural impulse is transmitted, Q. What is the...

Q. What is the mechanism by which the neural impulse is transmitted along the axon? The neural impulse is transmitted along the neuronal membrane through depolarization of cons

Explain therapeutic nutrition, Explain therapeutic  nutrition This ne...

Explain therapeutic  nutrition This necessitates dietitian's possessing a wide variety of skills. Beyond the technical knowledge and practical skills dietitians needs to have

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