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

Reproduction, name the sturcture formed when the male and female nuclei fus...

name the sturcture formed when the male and female nuclei fuse during fertilisation.

What ways farmers try to improve the quality of their soil, a) In what way...

a) In what ways do farmers try to improve the quality of (i) their soil, (ii) their crop plants?    b) What other steps do farmers take to maximise the yield from their

Volvox Colonial Existence, Necessity of interdependence of Volvox organisms...

Necessity of interdependence of Volvox organisms in the colonial existence

What is phylum hemichordata, What is Phylum Hemichordata ? The name "he...

What is Phylum Hemichordata ? The name "hemi"; (meaning "half") provides a clue to these animals, which have some of the features of chordates, and some features that are chara

Benefits of haccp, The benefits of HACCP  can be  summarized  as under. ...

The benefits of HACCP  can be  summarized  as under. a)  Benefits to Consumers Reduced risk of food borne diseases Increased confidence in food supply Increased awar

On which type of basis you classify the plants, Q. On which type of Basis y...

Q. On which type of Basis you classify the plants? Linnaeus mainly employed the characters of stamens and carpels and that is why the system is called as Sexual system of class

Define mitosis er and nucleolus, During mitosis ER and nucleolus begin to d...

During mitosis ER and nucleolus begin to disappear at: 1.  Late prophase 2. Early metaphase 3. Late metaphase 4. Early prophase Late prophase

What are biopolymers, Q. What are biopolymers? Polymers are macromolecu...

Q. What are biopolymers? Polymers are macromolecules made by the union of several smaller identical molecules, called monomers. Biopolymers are polymers present in the living b

Integumentary, What modern technology used for the integumentary system?

What modern technology used for the integumentary system?

Effect of metamorphic hormones on gene expression, Effect of Metamorphic Ho...

Effect of Metamorphic Hormones on Gene Expression Effect of metamorphic hormones on gene expression in moulting and metamorphosing insects, the first report of a particular ho

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