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

Explain in brief about life style modification, Explain in brief about Life...

Explain in brief about Life style modification Life style modification in simpler words, means  diet control and doing exercises. Diet control and exercise should be planned on

Explain human cells that produce proteins for exportation, What are some ex...

What are some examples of human cells that produce proteins for exportation? Which cytoplasmic organelle is expected to be well-developed and abundant in those cells? Specializ

Risk management option assessment, Risk management option assessment : ...

Risk management option assessment : Identification of available management options Selection of preferred management option , including consideration of an appropriate saf

Explain intensity of heart sound, Explain Intensity of heart sound? Int...

Explain Intensity of heart sound? Intensity of S 1, particularly M 1 depends on the position of the bellies of mitral leafets when the LV begins to contract since S 1 is loudes

Determine the types of cell, Determine the types of Cell Based OII the ...

Determine the types of Cell Based OII the degree of complexity of the cell organisation, two types of cells, namely, prokaryotes and eukaryotes, are recognised. The prokaryotic

Illustrate mitral valve orifice area, Q. Illustrate Mitral Valve Orifice Ar...

Q. Illustrate Mitral Valve Orifice Area? The normal mitral valve orifice in an adult is 4-5cm 2 when the valve is completely open in diastole. When the mitral valve orifice ar

Describe the basic working of cerebral hemisphere, Q. How is it structurall...

Q. How is it structurally explained that the motor activity of the left side of the body is controlled by the right cerebral hemisphere and the motor activity of the right side of

Assessment of peripheral vascular disorders - history, Assessment of Periph...

Assessment of Peripheral Vascular Disorders History Obtain the following information by interviewing the patient and family members Previous vascular surgery, previ

Differentiate between glycogenesis and glycogenolysis, Differentiate betwee...

Differentiate between glycogenesis and glycogenolysis. The synthesis  of glycogen in liver and muscle  is  called glycogenesis.  The breakdown of glycogen in the liver (glycoge

Explain th eobjective of intensive care, Explain th eobjective of intensive...

Explain th eobjective of intensive care? After reading this unit, you should be able to: • know how to organize an intensive care unit; • practice effective cardio pulmonary

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