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

Determine the function of osseointegration, Determine the function of Osseo...

Determine the function of Osseointegration Osseointegration is also a measure of implant stability, which occurs at two stages- primary and secondary. Primary stability has be

Explain red anthocyanin pigments, Explain Red anthocyanin pigments Red ...

Explain Red anthocyanin pigments Red anthocyanin pigments from miracle fruit were isolated and tested in carbonated beverages, in combination with the organic acids. Pigments d

What are two characteristics of joints unique, What are two characteristics...

What are two characteristics that make synovial joints unique and different from other joints?

What are the hormones secreted by the neurohypophysis, What are the hormone...

What are the hormones secreted by the neurohypophysis? What are their respective functions? The neurohypophysis secretes oxytocin and the antidiuretic hormone (ADH). Oxytoci

The hybridization reaction, As double-stranded DNA is heated a temperature ...

As double-stranded DNA is heated a temperature is reached at that the two reaction strands divided.  This procedure is called as denaturation.  The temperature at that half of the

Distinguish, distinguish between striated and cardic muscles

distinguish between striated and cardic muscles

Excretion in non-chordates, Excretion in Non-Chordates Excretion as de...

Excretion in Non-Chordates Excretion as described under Introduction of this unit refers to removal of the waste products of metabolism - carbon dioxide (CO 2 ) and water rele

Etiology, Etiology -Although this approach less desirable, it is useful...

Etiology -Although this approach less desirable, it is useful, short-term option if the etiology of the condition remains unknown. - The patient must inform about what will

Explain the different types of cells in cell structure , Explain the differ...

Explain the different types of cells in cell structure ? Types of Cells :  Cells can be classified as being either prokaryotic or eukaryotic depending on whether or not a mem

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