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

Transpiration, Most of the water taken up by a plant passes through it and ...

Most of the water taken up by a plant passes through it and is evaporated to the atmosphere.What use is made of the tiny fraction of this water which is retained by the plant?

Fruits why not glucose, Sucrose is commonly used to preserve fruits why not...

Sucrose is commonly used to preserve fruits why not glucose? Ans) Glucose is reactive due to its open-chain form having an aldehyde group.

Learning objectives of coronary artery disease, Q. Learning objectives of c...

Q. Learning objectives of coronary artery disease? • describe the various forms of coronary heart diseases, • enumerate the risk Factors (genetic and environmental) in causati

Where is the patient most likely to experience, The most recent blood work ...

The most recent blood work of a patient with a diagnosis of acute myelogenous leukemia (AML) reveals thrombocytopenia. Where is the patient most likely to experience abnormal bleed

Define alanine cycle, Alanine cycle Alanine Cycle  :  In the alanine ...

Alanine cycle Alanine Cycle  :  In the alanine cycle the pyruvate formed from glycolysis  in  the muscle is converted  to alanine by transamination  reaction. Alanine is rele

Define the nutritional assessment methods, Define the Nutritional assessmen...

Define the Nutritional assessment methods? Nutritional assessment methods commonly used are enumerated herewith. 1. Bodyweight measurement s remain to be the most practical

Nonsurgical retreatment will be the preferred choice, Nonsurgical retreatme...

Nonsurgical retreatment will be the preferred choice -Less invasive .. not cause problem to the pt. -Less traumatic postoperative .. most probably no post operative pain

Fatty Acids, How can I construct a fat molecule whose fatty acid tails are ...

How can I construct a fat molecule whose fatty acid tails are 4 carbon atoms long

Hazardous material - factors affecting occupational health, Hazardous Mater...

Hazardous Material - Factors Affecting Occupational Health Handling and storage of flammable and combustible liquids all the time pose threat to occupational safety. Fire and

Explain difficult feeding and poor growth, Explain Difficult Feeding and Po...

Explain Difficult Feeding and Poor Growth to recognition of congenital heart disease? Difficult Feeding and Poor Growth: The parent of an infant with CHD may complain that the

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