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.
What is Manifest Squint (Heterotropia) Manifest squint is a deviation of one eye from the normal position when the fusion reflex is present. The subcategories of manifest squin
what the by products of sugarcane
Define the Redia Larva? Redia is the third larval stage in the life cycle of F. heputicn. Redia develops from the germ cell Is of the sporocyst and comes out of the sporoc
What is Defective Colour Vision Defective colour vision is often called colour blindness. The ability to appreciate one or more of the primary colours is lacking. This can be e
Explain the term Kwashiorkor? The term Kwashiorkor means the 'disease the first child gets when the second baby is born', that is, 'the sickness of the deposed child'. Thus, th
when pollen tube enters the embryo-sac,it has;
Q. How different is the fish epidermis from the amphibian epidermis? The fish epidermis is very contains and thin mucus-secreting cells the fish skin doesn't present keratin, t
E mb ryonic stem cells (ES): These are pleuripotent cells of early embryo (blastocyst) capable of giving rise to all differentiated cells, including germ line cells. Em
Why does each skeletal muscle need an antagonistic partner? Because muscles can only contract and relax, each skeletal muscle requires an antagonistic partner to extend it afte
Advantages and disadvantages
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