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 the bio availability of vitamin a, Explain the Bio availability of ...

Explain the Bio availability of Vitamin A? By now it is clear that vitamin A is supplied in two forms. One form is retinol, from animal foods such as liver, fatty fish, eggs, a

What are the complementary base-pairing rules for biology, What are the com...

What are the complementary base-pairing rules for biology? In DNA, Adenine bonds with Thymine, Cytosine bonds with Guanine. In RNA, Thymine is changed with Uracil (bases capita

Original cell progresses to the g2, A cell in G1 of interphase has 12 chrom...

A cell in G1 of interphase has 12 chromosomes. How many chromosomes and DNA molecules will be found per cell when this original cell progresses to the G2?

Define features of fusarium - fungi and yeast, Define features of Fusarium ...

Define features of Fusarium - Identification of Fungi and Yeasts? Identifying features of Fusarium: 1. Wooly, white fuzzy colonies changing colour to pink, purple or yellow.

Determine the nutritional and functional role of minerals, Minerals :-Copp...

Minerals :-Copper Food Source      Organ meats, sea foods, nuts, seeds Nutritional Functional role Essential nutrient: Deficiency is rare. Catalyst: Lipid perox

Define the foam mat drying method, Define the Foam Mat Drying Method? T...

Define the Foam Mat Drying Method? This process is a development of the vacuum puffing but, instead of employing a vacuum to foam the material, it is initially foamed by suitab

Describe class echinoidea in animal kingdom, Describe Class Echinoidea in a...

Describe Class Echinoidea in animal kingdom? Sand dollars and sea urchins either have flattened disc-like bodies, or are somewhat spherical. While they lack the typical five-ar

Functions of colour in foods, Q. Functions of Colour in Foods? Let us n...

Q. Functions of Colour in Foods? Let us now look at the different functions of colour in details, which are enumerated herewith: 1. The maturity of many fruits and vegetable

What is risk, What is Risk  Risk  :  A function of the probability o...

What is Risk  Risk  :  A function of the probability of an adverse effect and  the magnitude of that  effect,  consequential to hazard(s)  in food.

Explain about the basidiomycota - fungi, Explain about the Basidiomycota - ...

Explain about the Basidiomycota - Fungi? Basidiomycota - Fungi in this division are called basidiomycetes or club fungi. Sexual structure is known as basidium, which is club-sh

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