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

What is dynamic auscultation in heart surgery, What is Dynamic Auscultation...

What is Dynamic Auscultation in heart surgery? It involves determining the effects on heart sounds and murmurs of various physiological and pharmacological manoeuvres, which al

Urine collection, Urine Collection: Untimed or random urine specimens ...

Urine Collection: Untimed or random urine specimens are suitable only for few chemical tests (mainly qualitative test). Usually urine sample is collected over a predetermined

Define about the composition of body weight, Define about the Composition o...

Define about the Composition of Body Weight? You might have read in previous units that our body weight is composed of muscle bone and fat. Segregating these components of body

Differences between cells of prokaryotes and eukaryotes, Differences betwee...

Differences between cells of Prokaryotes and Eukaryotes The prokaryotes also differ from the eukaryotes in many other ways, as you can see from Table. Table: Differences

Explain the sex composition of the population, Explain the Sex Composition ...

Explain the Sex Composition of the Population? Sex composition of human population is one of the basic demographic characteristics, which is extremely vital for any meaningful

Ecology, Explain how human activities can cause an imbalance in biogeochemi...

Explain how human activities can cause an imbalance in biogeochemical cycling and lead to problems such as cultural eutrophication and fish kills.

Buffers in foods, Some foods are better able to resist changes in pH than...

Some foods are better able to resist changes in pH than others. These tend to resist changes in pH since these are buffered and the ability to resist changes in pH is known as bu

Explain chemical structure of saponins, Explain Chemical Structure of sapon...

Explain Chemical Structure of saponins? Let us briefly understand their chemical nature. Their structures are characterized by the presence of a steroid or triterpene group, i.

Fats requirement in diabetes, Q. Fats requirement in diabetes? Fats: Th...

Q. Fats requirement in diabetes? Fats: The total fat recommended by WHO is less than 30% of the total calories. However in view of the widely prevalent Asian paradox in India,

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