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

Where are the adrenal glands located, Q. Where are the adrenal glands locat...

Q. Where are the adrenal glands located? How many are they and what are their portions? Each adrenal gland is located on the top of each kidney (forming a hat-like structure fo

Illustrate goal of modern dentistry, Q. Illustrate goal of modern dentistry...

Q. Illustrate goal of modern dentistry? The goal of modern dentistry is to restore the patient to normal contour, comfort, function, esthetics, speech and health regardless of

Cobalt (co) - micronutrients, Cobalt (Co) - Micronutrients The Co conc...

Cobalt (Co) - Micronutrients The Co concentration in the dry matter of plants grown in soil normally lies around 0.02 to 0.5 ppm. In soils the content varies from 1 to 40 ppm.

Proteins, assignment on the topic proteins

assignment on the topic proteins

What is the modern darwinist theory, In the time of Darwin the results of M...

In the time of Darwin the results of Mendel's research on biological inheritance had not been published, Genetics was not yet developed, neither DNA nor the concept of genetic muta

Explain the parasympathetic neurons, Which of the following serves as an ac...

Which of the following serves as an actuating signal, or as part of an actuating signal, in a negative feedback system? A. Action potentials in the fibers of the diaphragm musc

Question 1, Which type of reproductive structure has a better chance of sur...

Which type of reproductive structure has a better chance of survival if there was a sudden temperature change in its environment? A.)asci B.)zygosporangium C.)basidium D.)lichen

What do you understand by serial homology, What do you understand by Serial...

What do you understand by Serial homology? Metamerization results in a linear series of segments which share a common embryonic origin. Ancestrally, all metameres were identica

Estuaries - aquatic ecosystems, Estuaries - Aquatic Ecosystems All the...

Estuaries - Aquatic Ecosystems All the rivers and lakes ultimately drain into the sea. However, many rivers develop a highly specialised zone before joining the proper sea. Th

How do kidneys participate in the blood volume control, Q. How do kidneys p...

Q. How do kidneys participate in the blood volume control? How is the blood volume of the body related to the arterial pressure? The kidneys and the hormones that act upon them

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