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Sperm-egg
Sperm penetrating an ovum during fertilization
PhloxBotAdded by PhloxBot
File:Gray6.png
Diagram of a human sperm cell from Gray's Anatomy

The term sperm is derived from the Greek word (σπέρμα) sperma (meaning "seed") and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell. The human sperm cell is haploid, so that its 23 chromosomes can join the 23 chromosomes of the female egg to form a diploid cell. A uniflagellar sperm cell that is motile is referred to as a spermatozoon, whereas a non-motile sperm cell is referred to as a spermatium. Sperm cells cannot divide and have a limited life span, but after fusion with egg cells during fertilization, a totipotent zygote is formed with the potential to develop into a new organism.

The spermatozoa of animals are produced through spermatogenesis inside the male gonads (testicles) via meiotic division. They are carried out of the male body in a fluid known as semen. Mammalian sperm cells can live for up to 3 days inside the female reproductive system.[How to reference and link to summary or text]

Sperm cells in algal and many plant gametophytes are produced in male gametangia (antheridia) via mitotic division. In flowering plants, sperm nuclei are produced inside pollen.

Anatomy

File:Sperm2.svg
Structure of a spermatozoon

The sperm cell consists of a head, a midpiece and a tail. The head contains the nucleus with densely coiled chromatin fibres, surrounded anteriorly by an acrosome, which contains enzymes used for penetrating the female egg. The midpiece has a central filamentous core with many mitochondria spiralled around it, used for ATP production for the journey through the female cervix, uterus and uterine tubes. The tail or "flagellum" executes the lashing movements that propel the spermatocyte.

Sperm quantity=

=Psychological factors affecting sperm quantity

Sperm quality

Main article: Semen quality

Sperm quantity and quality are the main parameters in semen quality, which is a measure of the ability of semen to accomplish fertilization. Thus, it is a measure of fertility in a man.

Psychological factors affecting sperm quality

Market

Further information: Sperm donation

On the global market, Denmark has a well developed system of sperm export. This success mainly comes from the reputation of Danish sperm donors for being of high quality[1] and, in contrast with the law in the other Nordic countries, gives donors the choice of being either anonymous or non-anonymous to the receiving couple.[1] Furthermore, Nordic sperm donors tend to be tall and highly educated[2] and have altruistic motives for their donations,[2] partly due to the relatively low monetary compensation in Nordic countries. More than 50 countries worldwide are importers of Danish sperm, including Paraguay, Canada, Kenya, and Hong Kong.[1] However, the Food and Drug Administration (FDA) of the US has banned import of any sperm, motivated by a risk of mad cow disease, although such a risk is insignificant, since artificial insemination is very different from the route of transmission of mad cow disease.[3] The prevalence of mad cow disease is one in a million, probably less for donors. If prevalence was the case, the infectious proteins would then have to cross the blood-testis barrier to make transmission possible.[3] Transmission of the disease by an insemination is approximately equal to the risk of getting killed by lightning.[4]

Great Britain, on the other hand, as well as Sweden, has a sperm shortage, due to a ban of anonymous sperm donation.


See also

References

  1. 1.0 1.1 1.2 Assisted Reproduction in the Nordic Countries ncbio.org
  2. 2.0 2.1 FDA Rules Block Import of Prized Danish Sperm Posted Aug 13, 08 7:37 AM CDT in World, Science & Health
  3. 3.0 3.1 The God of Sperm By Steven Kotler
  4. A 'BABY BJORN' SPERM CRISIS NEW YORK POST. September 16, 2007

External links

Preceded by:
None
Stages of human development
Sperm
Succeeded by:
Zygote
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