Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
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.
Cytokinesis It is defined as the division or cleavage of cytoplasmic part of the cells into two daughter cells. It is first indicated during late anaphase by app
Q. Which Of substance are microfilaments made and what are the properties of these elements that give motility to cells? Microfilaments are made of actin a protein. The contrac
Explain the Naturally occurring Food Chemicals? Pharmacologically active substances include vasoactive amines such as histamine, tyramine, tryptamine, phenylethylamine, and ser
What are the Results of prosthetic valve endocarditis? The hospital mortality for valve replacement for endocarditis varies between 4- 30 per cent. Operative mortality is highe
E n z y m e - linked immunosorbent assay (ELISA): ELISA in its var io us modifications e.g. plate ELISA, sandwich ELISA, competitive ELISA, ELISA strip or
How does the intensity of facilitated diffusion vary in relation to the concentration of the moved substance? What is the limiting factor? Like simple diffusion facilitated dif
Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4
What is the compound that is phosphorylated for ATP formation? What is the resulting compound when ATP liberates energy? ATP, or adenosine triphosphate, is produced after the
Q. Nematode identity card. How are nematodes characterized according to examples of representing beings, type of symmetry basic morphology, , germ layers and coelom, digestive syst
Define measuring body composition- Total body potassium? It applies the' concept that body cells contain a constant amount of potassium and that its measurement is theref
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd