What is oogenesis , Biology

Assignment Help:

What is Oogenesis ?

The female sex cells, or eggs, are formed in the ovaries, the primary sex organs of the female. The precursor of the egg cells, or oogonia, are formed during the prenatal development of the ovaries in the female embryo. However, the oogonia do not increase in number until after the third month of fetal development.

Oogonia divide by mitosis to form primary oocytes. These cells gradually die off, but about 200,000 are left in each ovary at puberty (about 11 to 14 years of age). Over the course of a woman's reproductive life, only about 450 oocytes will mature completely into eggs.

The primary oocyte begins meiosis, undergoing a very unequal division in which the larger cell becomes a secondary oocyte, and the other forms the first polar body, which eventually dies off. The second meiotic division, also unequal, forms a haploid ootid and a second polar body that also dies off. What is left is a single haploid egg cell or ovum (plural ova) that is 75,000 times larger than a sperm cell. The ovum contains contains proteins, lipids, and other raw materials for development. It is thought that the reason 3 of the 4 cells that result from meiosis die off is to provide the one surviving egg with sufficient resources for development.

 


Related Discussions:- What is oogenesis

What are organogenesis and histogenesis, Q. What are organogenesis and hist...

Q. What are organogenesis and histogenesis? Histogenesis is the procedure of tissue formation in the embryonic development. Organogenesis is the procedure of organ formation. B

In which lysosomic enzymes play a fundamental role, Q. What are the various...

Q. What are the various biological examples in which lysosomic enzymes play a fundamental role? The remodelation of the osseous tissue, the function of the elimination of the t

Explain about the biofertilizers, Explain about the Biofertilizers Biof...

Explain about the Biofertilizers Biofertilizers, are the cultures of microorganisms used for inoculating seed or soil or both under ideal conditions to increase the availabilit

What is the genotypical proportion of the gametes, Which is the type of gam...

Which is the type of gamete (for a given trait) produced by a dominant homozygous individual? What is the genotypical proportion of these gametes? What about a recessive homozygous

What is the cytoskeleton, Q What is the cytoskeleton? What are its major co...

Q What is the cytoskeleton? What are its major constituents in animal cells? Cytoskeleton is the cytoplasmic structure that supports the cell, keeps its fixates and shape and m

Drought-water stress and adaptations, Drought Drought refers to a condi...

Drought Drought refers to a condition of water shortage and it can result from many reasons. Frequently less than the normal rainfall is a common cause of drought. Less than 75

Final energetic products of every round of the krebs cycle, Q. What are the...

Q. What are the final energetic products of every round of the Krebs cycle? And Where is most part of the utile energy at the end of Krebs cycle found? After each round of the

Measures of evenness, Measures of Evenness The maximum Shannon-Wiener i...

Measures of Evenness The maximum Shannon-Wiener index for a given number of species can be calculated as: The minimum Shannon-Wiener index for a given data set can be c

What is the energy source used in active transport, Q. What is the energy s...

Q. What is the energy source used in active transport through biological membranes? The energy necessary for active transport against the concentration gradient of the transpor

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