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 phrase best describes oxidation- reduction reaction, What phrase best ...

What phrase best describes oxidation- reduction reaction? A. phosphoryrylation energezing endergounic reactions b. transferring of electrons from one molecule to another c. shar

Define natural adulteration - types of adulteration, Define Natural Adulter...

Define Natural Adulteration - Types of Adulteration? These are the chemicals, organic compounds or radicals which are naturally present in the food and are harmful to the healt

Vitamin a requirements of school children and adolescents, Determine Vitami...

Determine Vitamin A requirements of school children and adolescents? The vitamin A requirement of children and adolescents has been computed from growth curve interpolation dat

Nerve fibres, NERV E FIBRES - Axon or dendrite of a nerve cell cove...

NERV E FIBRES - Axon or dendrite of a nerve cell covered with one, two or three sheaths is called nerve fibre. Dendrites are surrounded only by one sheath. An axon may b

Define the miscellaneous applications of sugar, Define the Miscellaneous Ap...

Define the Miscellaneous Applications of Sugar? Sugars are used in 1. Custards, 2. puddings, 3. pie fillings and meringues Depending on the sugar to perform vital c

What is the role of radiographic evaluation, What is the role of radiograph...

What is the role of radiographic evaluation in implant treatment? Radiographic examination is very different with implants than with teeth. Radiographs are frequently used in i

What are the hydrophobic molecules, Q. What are the hydrophobic molecules (...

Q. What are the hydrophobic molecules (or hydrophobic molecular regions)? What are the hydrophilic molecules? How can they be characterized in relation to their polarity? Hydro

Define modulation of transcription of cell cycle proteins, Modulation of th...

Modulation of the transcription of cell cycle proteins? The 1,25-(OH),D  compound (calcitriol), is present in the blood complexes to the vitamin D-binding  protein, a specific

Multidisciplinary approach to solving nutrition problems, Define Multidisci...

Define Multidisciplinary Approach to Solving Nutrition Problems? You must have realized by now that solving public nutrition problems represents a multidisciplinary challenge o

Glycogenesis, Glycogenesis :   This  is an anabolic process  in which  gluc...

Glycogenesis :   This  is an anabolic process  in which  glucose is polymerized  into glycogen by the   sequence of  reactions.  Since glycogenesis occur  in all  body  cells .but

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