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Encyclopedia > Sperm cell
Schematic diagram of a sperm cell, showing the (1) , (2) , (3) , (4) , and (5) (tail)
Schematic diagram of a sperm cell, showing the (1) acrosome, (2) cell membrane, (3) nucleus, (4) mitochondria, and (5) flagellum (tail)

A sperm cell, or spermatozoon (pl. spermatozoa) (in Greek: sperm = semen and zoon = alive), is the haploid cell that is the male gamete. It is carried in fluid called semen, and is capable of fertilising an egg cell to form a zygote. A zygote can grow into a new organism, such as a human. Sperm cells contain half of the genetic information needed to create life. Generally, the sex of the offspring is determined by the sperm, through the chromosomal pair "XX" (for a female) or "XY" (for a male). Sperm cells were first observed by Antoni van Leeuwenhoek in 1679.


Sperm structure and size

Individual spermatozoa are highly differentiated cells, composed normally of a head, basal body (or midpiece), and tail. The head contains some cytoplasm and the nuclear material for fertilization. The basal body contains a large concentration of mitochondria that provide the energy for sperm motility through the production of ATP. The spermatozoan tail is typically a flagellum used for propulsion.


In humans, sperm cells consists of a head 5 Ám by 3 Ám and a tail 50 Ám long. The tail flagellates, which propels the sperm cell. The cell is characterized by a minimum of cytoplasm.


Sperm production

Main article: Spermatogenesis


Sperm are produced in the seminiferous tubules of the testes in a process called spermatogenesis. Round cells called spermatogonia divide and differentiate eventually to become sperm. During sexual intercourse the sperm is deposited in the vagina - and then it moves to the ovum.


External link

  • The Handbook of Andrology (http://www.andrologysociety.com/resources/handbook.asp)

  Results from FactBites:
 
John Gatewood MD, vasectomy reversal - Sperm Antibodies (316 words)
The sperm, however, does not develop until puberty and is isolated from the immune system in the ductal systems of the testicle and epididymus and vas.
Sperm, which are coated heavily with antibodies, cannot penetrate the cervical mucus and cannot reach the egg to fertilize it.
Even though sperm antibodies are detected in the semen, they might not be at a high enough level as to cause impairment of fertility, and therefore not be clinically significant.
  More results at FactBites »

 
 

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