Sperm Structure
Sperm cells are gametes or sex cells that are produced in the testicular organ or gonad of male human beings and animals.
Like the female gamete, sperm cells carry a total of 23 chromosomes that are a result of a process known as meiosis. In both animals and human beings, among many other organisms, these cells are involved in the sexual mode of reproduction, which involves the interaction of male and female gametes.
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A normal sperm will have the following characteristics:
- A smooth oval head - The head of a normally formed sperm has a smooth surface and resembles the shape of an egg
- The head of the sperm measures 2.5 to 3.5 um in diameter and 4.0 to 5.5 um in length (um=micrometers). This results in a 1.50 to 1.70 length to width ratio
- They have a well-developed acrosome that covers 40 to 70 percent of the oval shaped head
- A slim middle section (body) that is approximately the same length as the head
- A thinner tail section that is about 45 micrometer in length
Now let’s see the structure of sperm in detail:
A sperm cell consists of a head, body (mid-section) and a tail. Each of these parts is equipped with various molecules and smaller structure that allow the sperm as a whole to function properly.
Sperm Head
The head is the most important part of the cell given that it contains the nucleus (genetic material with 23 chromosomes) required to form a new organism.
Apart from the nucleus, the head is also made up of a several parts that include:
Acrosome and acrosomal cap:
Together, the two (acrosome and acrosomal cap) make up the acrosomal region. Formed during spermiogenesis, the acrosome is the product of Golgi complex and contains a number of contents such as acrosin enzyme in the acrosomal matrix. Apart from the enzymes, the acrosome also contains such polysaccharides as mannose, hexosmine and galactose.
The acrosome plays a number of important roles in fertilization. For instance, with a number of its associated molecules, the acrosome is involved in the recognition of the oocyte (egg) to be fertilized.
Midpiece
The midpiece is the central part of the sperm cell between the head and the tail. Like the head, the midpiece makes up about 10 percent of the total sperm length. Unlike the sperm head that carries genetic material, the midpiece contains tightly packed mitochondria that provide the energy requires for swimming.
In addition to providing the energy required for swimming, mitochondria is also suggested to play a role in controlled cell death known as apoptosis.
Centriole - The centriole is part of the sperm cell located between the head and the midpiece. In a complex referred to as the centriole-centrosome complex, the centriole is involved in the formation of sperm aster and zygote aster.
These are essential for movement of the pronuclear for union with the female genome. Moreover, the centriole is involved in the production of mitotic apparatus involved in separating chromosomes during cell division while at the same time being the template for all subsequent centrioles.
Tail
The sperm tail is a thin, elongated structure that makes up about 80 percent of the entire length of the sperm.
While the tail may appear to be one long continuous structure, it is divided into several parts that include:
- Connecting piece – This is the part that connects the flagellum to the sperm head
- Mid piece - It contains mitochondria and thus provided the energy required for movement
- Principal piece (axial filament)
- End piece
* The principal piece and the end piece of the flagella help generate the waveform that allows for movement.
Sperm cells, gamete या sex cells होती हैं जो human male के testicular organ या gonad में उत्पन्न होती हैं। female gamete की tarah sperm cell मे 23 chromosome होती है , जो meiosis cell division के परिणामस्वरूप होती हैं।
Animals और humans ke साथ, कई अन्य जीवों के बीच, ये cells, sexual mode of reproduction मे involve होती है, जिसमें male और female gametes का interactions होता है।
एक normal sperm मे following characteristic होती है ।
एक normally formed sperm का head smooth oval shape का होता है।
Sperm head का diameter 2.5 se 3.5 um और length 4 se 5.5 um होता है ।
Sperm मे well-developed acrosome होता है, जो approx. 40-70 % oval shape head को cover करता है।
Sperm मे एक thin middle section hota hai जिसका length लगभग head के length के equal होता है ।
इसके अलावा एक thin tail section होता है, जो लगभग 45 micrometer का होता है।
आइये अब detail मे sperm के structure को देखते है।
Sperm head:
Head, sperm का सबसे important हिस्सा होता है, जिसमे एक new life form करने के लिए अवस्यक nucleus होता है, जिसमे 23 chromosome होता है।
Nucleus के अलावा sperm का head कई अन्य part से बना होता है जिसमे acrosome और acrosomal cap शामिल है।
Acrosome and acrosomal cap:
Acrosome और acrosomal cap मिलकर acrosome region का formation करता है। spermeiogenesis के दौरान Golgi complex से acrosome का formation होता है। acrosome के matrix मे Acrosine enzyme मिलता है। Acrosine enzyme के अलावा acrosome me mannose, hexosmine, और galactose भी होता है।
Acrosome fertilization मे बहुत important Role play करता है जैसे की इसके ऊपर present molecules oocyte को fertilization के लिए identify करता है।
Midpiece
Midpiece sperm का एक central part है, जो sperm head और tail के बीच मे होता है। Sperm head की तरह midpiece sperm की कुल लंबाई का approx. 10 % है ।
Sperm के midpiece मे tightly packed mitochondria होता है, जो स्पर्म को swim करने के लिए आवस्यक energy provide करता है।. sperm को energy provide करने के अलावा mitochondria controlled cell death जिसे apoptosis कहते हैं उसे भी control करता है। Centriole: centriole sperm का वह हिस्सा है जो sperm के head और midpiece के बीच मे होता है।centriole centrosome complex मे centriole sperm aster aur zygote aster ka formation करता है। इसके अलावा centriole mitotic apparatus का भी formation करता है, जो mitosis cell division के दौरान chromosome को separate करता है।
Tail
Sperm का tail thin, elongated structure है जो पूरे sperm के length का 80% है।
Although sperm tail एक long continuous structure है, but sperm tail को कई भागों मे divide किया गया है। जैसे की-
Connecting piece: - connecting piece sperm tail का वह हिस्सा है जो flagella को sperm head से connect करता है। इसके अलावा
Mid piece, principal piece aur end piece होता है।
Principal piece aur end piece waveform को generate करने मे मदद करता है जो sperm के movement मे help करता है।
