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

Radiometer-radiation instrument, Radiometer Radiometer measures the flu...

Radiometer Radiometer measures the flux of energy of all wavelengths received on a single surface of the receiver. There are also instruments that can measure the difference be

How can the visual deficiencies known as myopia, How can the visual deficie...

How can the visual deficiencies known as myopia and hypermetropia be optically explained? Myopia is the visual condition in which the images are produced before (in front of)

Ecosystem balance, Ecosystem Balance We take up, another parameter of ...

Ecosystem Balance We take up, another parameter of ecosystem balance. One factor that affects the stability or persistence of some ecosystems under small or moderate environme

Chromosomes in a cell, Two chromosomes in a cell have identical length and ...

Two chromosomes in a cell have identical length and centromere position yet are not homologous, what is different about them

Concept of digestion in the stomach, Digestion in the Stomach To unders...

Digestion in the Stomach To understand  the digestion mechanism  in the stomach, it is important to know about the anatomy of the stomach. Look up Unit 6, in the Applied Physio

Extremes of heat and cold, Extremes of Heat and Cold Deserts are region...

Extremes of Heat and Cold Deserts are regions of aridity with rainfall of less than 20 cm per year and the soil, though L, fertile, is too porous to retain any water. In summer

Nursing process in infective endocarditis, Nursing Process Nursing Ass...

Nursing Process Nursing Assessment Health history-Past-valvular, congenital or syphilitic cardiac disease/cardiac surgery. Habits-IV drug abuse. Assess the signs an

Types of hormones, T ypes of hormones - (i) Releasing and Inhibitory ...

T ypes of hormones - (i) Releasing and Inhibitory hormones - Hormones of hypothalamus and kidney (renin) which control secretion of trophic hormones. (ii) Trophic hormon

Frequency - synthetic characters, Frequency - Synthetic Characters Thi...

Frequency - Synthetic Characters This term refers to the degree of dispersion of individual species in an area, and is usually expressed in terms of percentage. Frequency can

What is the predicted cell morphology, What are the predicted cell morpholo...

What are the predicted cell morphology, cell arrangement and gram stain results for each of the follow? 1. Bacillus megaterium 2. Staphylococcus aureus 3. Serratia marcesc

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