Sperm or spermatozoon


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Structure of sperm 

A mature sperm or spermatozoon is consist of 4 parts.

1. Head 

2. Neck 

3. Middle piece 

4. Tail 


1. Head:

It is fate and ovel in human sperm. It is composed of a large posterior nucleus and a small Acrosome. Acrosome is formed from the golgicomplex. The nucleus consist only of condence DNA and basic proteins. It consist of hydrolytic enzymes and is used to contact and penetrate the egg in fertilization.


2. Neck:

The neck is very short and contains two centriole lying one behind and at right angles to the other. The proximal centriole plays a role in the first cleavage of zygote. A distal centriole gives rise to the axial filament of the sperm.


3. Middle Piece:

The middle piece of human sperm is cylindrical structure. It contains many mitochondria tightly coiled roundly axial filament. The mitochondria provide energy for the movement of the sperm in the female genital tract . Middle piece therefore is also termed as power house of spermatozoon. The amount of energy available is limited. If a sperm failed to contact an ovum with a specific period (24 to 48) hours it exhaust it's energy and dies.


4. Tail:

The tail is very long, cylindrical, tapering and is formed of cytoplasm. A fine thread, the axial filament arises from the posterior centriole and traverse the middle piece of tail.


  The. Entire sperm is enclosed by a plasma membrane. The spermatozoa swim about by vibrating tail in a fluid medium in search of ova.





 

Difference between spermatogenesis and Oogenesis




SpermatogenesisOogenesis
1. Spermatogenesis occurs in the male gonads testes.
2. Growth phase is sort. So that spermatosites are only twice size of spermatogonia.
3. Spermatosites have cytoplasm and Nucleus with normal contents.
4. A primary spermatosites divides equally to two similar spermatids.
5. Secondary spermatosites also divide equally forming two similar spermatids.
6. Upto the formation of spermatids the cells of an remain interconnected.
7. A spermatogonia produces four functional spermatozoa.
8. Spermatogenesis is of an continuous process.
9. In man sperm mother cells continue to multiply through out life
1. Oogenesis occurs in ovary.

2. Growth phase is very long so that, oosites are much larger than Oogonia.
3. Oocytes have cytoplasm rich in RNA , ATP , enzymes and Yolk and Nucleus with giant chromosomes and large nucleoli.
4. A primary oocytes divides unequally to form one large secondary oocytes and one minute polar body.
5. A secondary oocytes also divides unequally forming one large oocytes and one minute polar body.
6. Oogonia are separate and surrounded by follicle cells.
7. Oogonia produces one functional ovum and three non functional polar bodies.
8. Oogenesis has. Long resting periods.
9. In female ovary has at birth all the egg mother cells. It will ever have.
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