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 nutrition or diet counseling, Explain Nutrition or diet counseling ...

Explain Nutrition or diet counseling Nutrition or diet counseling  is a  primary educational activity  of  the dietitian.  It incorporates the idea of working with a patient, e

Air pollution- introduction, Air pollution is complex in origin and varied ...

Air pollution is complex in origin and varied in effect. It is very crucial from the point of human health. Every human being inhales about 15-22 kg of air daily and air is pollute

Define the antigen-presenting cells of the immune system, Q. What are the a...

Q. What are the antigen-presenting cells of the immune system? The antigen-presenting cells of the immune system also known as APC cells are cells that do digestion and phagocy

Skeletons of radiolarians, Skeletons of radiolarians The skeletons of ...

Skeletons of radiolarians The skeletons of radiolarians and foraminiferans form a primary constituent of ocean bottoms where they form 30% or more of the sediment. It is calle

What is the probability of carrier of the recessive allele, Two parents who...

Two parents who are each known to be carriers of an autosomal recessive allele have four children. None of the children has the recessive condition. What is the probability that

What is hypertension, Q. What is hypertension? The Hypertension is a di...

Q. What is hypertension? The Hypertension is a disease in which the arterial blood pressure, during systole or during diastole, is abnormally high. The Hypertension, or high

Treatments of coronary, The treatment of hyperlipidemia requires two approa...

The treatment of hyperlipidemia requires two approaches: Therapeutic lifestyle changes (TLC) and medications. To achieve target LDL levels, most patients need both approaches si

Define the roller drying (drum drying) method, Define the Roller Drying (Dr...

Define the Roller Drying (Drum drying) Method? One of the important techniques for drying liquid food products is the roller drier. Like spray drying, roller drying can only be

What are the types of muscle tissues, What are the types of muscle tissues?...

What are the types of muscle tissues? What are the morphological features that differentiate those types? There are three kinds of muscle tissue: the skeletal striated muscle t

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