What is the length of the Human spermatozoa (Sperm)?
a. 50 micrometers
b. 100 micrometers
c. 200 micrometers
d. 500 micrometers
The Correct option is A
Explanation with High Yield Facts:
The measurements of different parts of spermatozoon:-
- Head - 4.0 μm
- Neck - 0.3 μm
- Middle piece - 7 μm
- Principal piece - 40 μm
- End piece - 5-7μm
- Approximately 58.3μm
As it is released from the wall of the seminiferous tubule into the lumen, the spermatozoon is non-motile but structurally mature. Its expanded head contains little cytoplasm and is connected by a short constricted neck to the tail.
The tail is a complex flagellum and is divided into middle, principal and end pieces. The head contains the elongated flattened nucleus with condensed, deeply staining chromatin and the acrosomal cap anteriorly, which contains acid phosphatase, hyaluronidase, neuraminidase and proteases necessary for fertilisation. In the centre of the neck, is a well formed centriole, corresponding to the proximal centriole of the spermatid from which it differentiated. The axonemal complex is derived from the distal centriole.
A small amount of cytoplasm exists in the neck covered by plasma membrane continuous with that of the head & tail.
The middle piece - a long cylinder - consists of an axial bundle of microtubules, the axoneme, outside which is a cylinder of nine dense outer fibres, surrounded by a helical mitochondrial sheath.
The annulus is an electron - dense body at the caudal end of the middle piece. The principal piece - motile part of cell - The axoneme and the surrounding dense fibres are continuous from the neck region through the whole length of the tail except for its terminal 5- 7μm, in which the axoneme alone persists. The end piece has a typical structure of a flagellum, with a simple nine plus two arrangement of microtubules.
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