sperm

Also known as spermatozoa or spermia. Male gamete or sex cell, posessing a motile flagellum for movement and a pointed head consisting mainly of nucleus. The base of the flagellum is lined with numerous mitochondria for powering movement; these organelles are discarded before the sperm penetrates the ovum. Enzymes present in the acrosome or 'nose' part of the sperm act on the outer parts of the ovum, altering it's properties so that a sperm may evenually penetrate - note that the enzymes from many hundreds of sperm are required for this task.

Note that, despite what Webster says, sperm is NOT semen (although the term sperm is sometimes used instead of semen - usually anong teens).
During spermatogenesis, sperm do not become motile until sometime during their journey down the tail of the epididymis. Once ejaculated, sperm are very active, and can move as fast as 20 microns a second. The flagellum makes whipping, undulatory movements, causing the sperm to rotate about it's long axis as it moves forward.

Sperm cels are the smallest in human body (roughly 175,000 sperm are needed to match the weight of one egg cell) and here are about 60,000 sperm per mm^3 of ejaculate. Sperm may survive outside the body for several days. They can survive in the fallopian tubes for a similar amount of time, and can be (and have been) extracted alive from the ejaculatory ducts some days after death.

Sperm produced in the walls of the seminiferous tubule in the testis. The production of sperm is called spermatogenesis. Men produce sperm from puberty onwards, continuously. Each normal ejaculation contains from 100 to 650 million sperm cells. A man can ejaculate daily with little loss of fertilizing capability.
The human sperm (along with many other species) is made of a head, middle piece and a tail.

Head:
At the tip of the head is the acrosome (a special body containing enzymes), a nucleus(containing genetic information to pass on to the offspring) and a centriole. The shape varies form species to species, humans being an oval shape, while others are comma shaped or spherical.

Middle Piece:
Contains many mitochondria, or in other species a large single one. These provide the energy for the tail.
Note: The sperm mitochondria are not allowed into the egg upon fertilization, which is why mitochondrial inheritance is maternal.

Tail:
A long whip like structure, covered by a plasma membrane, used for transportation, by moving back and forth. Also called a flagellum.

Sperm determines the sex of the offspring, as it can contain either an X or Y chromosome.

What can kill sperm?

Intense or prolonged exposure to light. Notice that invitro fertilization labs (as shown on TV) usually have reduced light.

Acidic environments, like those found in the vagina. This is why ejaculate is basic, to help neutralize the deadly acid.

Heat. This is why the testes hang down from the body, to keep them cooler.

History:
It was once believed by sermists that ALL the heritable information was contained in the sperm. Shortly after the invention of the microscope (not a terribly powerful microscope), the spermists thought it had been proven once and for all. When they looked through the microscope at the sperms they saw a tiny little fetus in the head of each one.
Then the microscopes got more powerful...

Sperm (?), n.[F. sperme, L. sperma, Gr. , , from to sow. Cf. Spore.] Physiol.

The male fecundating fluid; semen. See Semen.

Sperm cell Physiol., one of the cells from which the spermatozoids are developed. -- Sperm morula. Biol. Same as Spermosphere.

 

© Webster 1913.

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Sperm, n.[Contr. fr. spermaceti.]

Spermaceti.

Sperm oil, a fatty oil found as a liquid, with spermaceti, in the head cavities of the sperm whale. -- Sperm whale. Zool. See in the Vocabulary.

 

© Webster 1913.