Oogenesis in mammals, Biology

Assignment Help:

Oogenesis in Mammals

In mammals also the oogonial cells are derived from primordial germ cells. The multiplication phase, that is all of the oogonial divisions and transformation of oogonia into oocyte are completed either before or shortly after birth. A number of oocytes are produced, all of which are held in meiotic arrest in prophase I.

Essentially in mammals the period of oogenesis covers the entire life of an individual from birth to ovulation. The meiotic arrest is released at the time of puberty after which a group of oocytes begin development during each cycle. A large percentage of oocytes fail to undergo maturation and therefore degenerate. The oocytes in mammals are found in close association with non-germ cells in the ovary. The non-germ cells or the accessory cells produce steroid hormones, transport some of the essential cytoplasmic components into the oocyte and are also involved in the formation of cellular or non-cellular layers that surround the fully differentiated egg. The accessory cells that surround the egg are of two types -

(1) Follicle cells,

(2) Nurse cells.

The follicle cells are somatic cells which surround the oocyte as a single layer of the cells and are known as follicular epithelial cells. The nurse cells are derived from germ cell line and are connected with the oocyte by cytoplasmic bridges. During the growth of the oocyte, the single layered follicular epithelium proliferates and becomes multilayered and the cells are called granulosa cells. The granulosa cells and the oocyte are separated by a space which is filled with sulphated glycoproteins. This layer becomes the zona pellucida of the oocyte. When proliferation of the granulosa cells is completed they secrete a fluid that accumulates in the intercellular spaces. The fluid filled spaces coalesce to form a cavity called antrum.


Related Discussions:- Oogenesis in mammals

What characteristics of fatty acids are false, What characteristics of fatt...

What characteristics of fatty acids are false? (Dissolves in water, used for energy storage, used to build lipids, found in triglycerides, found in steroids)?

What''s the diffrence between regeneration and repair, What's the diffrenen...

What's the diffrenent between regeneration and repair ?  Regeneration: replacement of the destructed tissue by the same type of tissue  Repair : replacement of the destru

Is water a non-polar or a polar molecule, Q. Is water a non-polar or a pola...

Q. Is water a non-polar or a polar molecule? What is the consequence of that characteristic for the function of water as solvent? Ans. Water is made of two atoms of hydrog

Energetic function of organic molecules, Q. What are the few examples of th...

Q. What are the few examples of the energetic function of organic molecules? Ans. Since they are complex molecules, organic molecules store large amount of energy, present

Explain hypertensive disorders of pregnancy, Explain Hypertensive Disorders...

Explain Hypertensive Disorders of Pregnancy? Hypertension may have been existing before pregnancy. Alternatively, a mother may develop hypertension during pregnancy, a pregnanc

Define hydroxybenzoic acid and hydroxycinnamic acid, Define Hydroxybenzoic ...

Define Hydroxybenzoic acid and Hydroxycinnamic acid? Hydroxybenzoic acid: e.g. ellagic and gallic acids, which are hydrolyzable tannins, present in berries and nuts. Hydroxy

Zoonoses disease- histoplamosis, Histoplamosis Caveran disease, darling’s ...

Histoplamosis Caveran disease, darling’s disease, reticuloendothelial cytomycosis or tingo maria fever are the other synonyms for histoplamosis caused by Histoplasma capsulatum. T

Autoradiography, Autoradiography Autoradiography is a modification of t...

Autoradiography Autoradiography is a modification of the radioactive tracer technique. In this technique, the radioactivity is detected by a thin film of photographic emulsion

While meiosis results in four diploid cells, Which of the following best co...

Which of the following best compares the results of mitosis and meiosis? Mitosis results in four diploid cells, while meiosis results in two haploid cells. Mitosis results in four

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