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 is parasitism, Q. What is parasitism? The Parasitism is the ecolog...

Q. What is parasitism? The Parasitism is the ecological interaction in which a being lives at the expense of another. The parasite often doesn't cause immediate death of the ho

Define method used for capsular staining - anthony staining, Define method ...

Define method Used for Capsular Staining - Anthony Staining Method? Another method used for capsular staining is Anthony staining method, devised by E.E. Anthony in 1931. The m

Explain briefly about vitamin B12, Vitamin B 12 (Cyanocobalamin) Vitam...

Vitamin B 12 (Cyanocobalamin) Vitamin B 12 refers to a group of Cobalt-containing corrinoids known as cobalamins. It is also called antipernicious- anemia factor, extrinsic f

Compare and contrast the effect of a deletion, Compare and contrast the eff...

Compare and contrast the effect of a deletion in the operator of the lactose operon with one in the operator of the histidine operon.

Explain zymogen, Zymogen :- an  inactive form of an  enzyme; becomes active...

Zymogen :- an  inactive form of an  enzyme; becomes active prior to its action.

Explain methodology required for osazone test, Explain Methodology Required...

Explain Methodology Required for Osazone Test? Take about 250-300 mg of phenylhydrazine mixture in the 3 clean labelled 15 ml dry test tubes. Add 5 ml of the glucose, fructose

To test the effects of temperature on the activity of yeast, To test the ef...

To test the effects of temperature on the activity of yeast Make up a quantity of bread dough .Stir a yeast cake in water and methodically mix the yeast with the dough. Divide

Organisation of nervous system, Organisation of Nervous System Nervou...

Organisation of Nervous System Nervous systems are composed of nerve cells or neurons and glial cells. In the latter half of the 19 th century it was strongly believed that

Growth-form and structure, Growth-form and Structure In a community the...

Growth-form and Structure In a community the number of species and size of their populations vary greatly. A community may have one or several species. The environmental factor

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