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 are the problems regarding terrestrial environment, Q. What are the pr...

Q. What are the problems that vertebrates needed to solve to adapt to the terrestrial environment since they came from the aquatic habitat? How evolution does solve those problems?

Why fats have highest heat energy density, Why Fats have highest heat energ...

Why Fats have highest heat energy density? Fats have highest heat energy density of 9 Kcal/g. It is the major storage form of energy in body requiring least space and minimum w

Chromolipid, CHROMOLIPID Formed by lipid & pigment, eg. carotene, xanth...

CHROMOLIPID Formed by lipid & pigment, eg. carotene, xanthophylls. Lycopene present in tomato & red chilli. Carrot is rich in b-carotene, converted into vitamin A.

Planning of nursing care - acute glomerulonephritis, Planning of Nursing Ca...

Planning of Nursing Care   Provide supportive and symptomatic treatment.  Provide bed rest.  Encourage diet restriction,  Implementation  of Nursing Care

Risk analysis - animal studies, Animal studies Most toxicological data ...

Animal studies Most toxicological data for risk assessment are derived from the animal studies and  it  is, therefore, essential that these studies be conducted following widel

How different are the concepts of neoplasia-tumor and cancer, Q. How differ...

Q. How different are the concepts of neoplasia, tumor and cancer? Not all tumor is neoplastic and not every neoplasia creates tumor. The Tumor is the generic name given to the

What are the apical meristems, What are the apical meristems? Which kind of...

What are the apical meristems? Which kind of plant growth does this meristem promote? The Apical meristems are those primary meristems found in the apex of the stem as well as

Original density in CFU/ML, a nutrient agar plate labelled 10^(-5)ml had 15...

a nutrient agar plate labelled 10^(-5)ml had 154 colonies after incubated. what is the cell density in the original sample

Classification of protein based on shape, Protein Classification Based on S...

Protein Classification Based on Shape There are three types of proteins on the basis of shape - Fibrous, Globular, Intermediate 1 .       FIBROUS PROTEINS They ar

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