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

Carbohydrates requirement in pectic ulcer, Q. Carbohydrates requirement in ...

Q. Carbohydrates requirement in pectic ulcer? Carbohydrates: These should provide around 55 to 65% of the daily intake. Emphasis - J should be laid on the consumption of 60th s

Popularity of chromatography - basic separation technique, Define Popularit...

Define Popularity of Chromatography - Basic Separation Technique? Chromatography is popular because: (a) minute quantities can be analysed qualitatively and quantitatively,

Difference between an ecological niche and a habitat, What is the differenc...

What is the difference between an ecological niche and a habitat? An ecological niche is a set of peculiar activities, resources and methods that a species explores to survive

Food borne infections, Q. Food borne infections? Food borne infections,...

Q. Food borne infections? Food borne infections, as you may recall reading earlier, are caused by the ingestion of pathogenic microorganisms that penetrate the intestinal muco

Determine the term - chlorine, Determine the term - Chlorine   The appl...

Determine the term - Chlorine   The application of chlorides results in leaves of greater spread, a lighter green colour and with a smoother surface. However, the combustibilit

Brain, How brain thinks?

How brain thinks?

Illustrate erythropoietin, Define Erythropoietin A. acts by stimulating...

Define Erythropoietin A. acts by stimulating the production of red blood cells by the peritubular interstitial cells of the kidney cortex. B. is secreted by cells in the bon

Explain the term - social attention and environmental influe, Explain the t...

Explain the term - Social Attention and Environmental Influences The importance of social environment and early experiences in neurodevelopment is increasingly recognised. Due

Define body mass index (bmi), Define Body Mass Index (BMI)? Weight for ...

Define Body Mass Index (BMI)? Weight for height as a marker of nutritional status has the advantage that it is independent of other factors that affect foetal outcome such as m

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