Anisogamy
1544170
222576397
2008-06-30T02:12:44Z
Qef
72915
Use new SVG version of image
[[Image:Anisogamy.svg|thumb|Different forms of anisogamy: A) anisogamy of motile cells, B) oogamy (egg cell and sperm cell), C) anisogamy of non-motile cells (egg cell and spermatia)]]
'''Anisogamy''' (also called '''[[heterogamy]]''') refers to a form of [[sexual reproduction]] involving [[gamete]]s of different sizes. The smaller gamete is considered to be male ([[Sperm|sperm cell]]) whereas the larger gamete is regarded as female ([[Ovum|egg cell]]).
There are several types of anisogamy. Both gametes may be [[Flagellum|flagellated]] and thus motile. Conversely, neither of the gametes may be flagellated. This situation occurs for example in some algae and plants. In the [[red alga]] ''Polysiphonia'', large non-motile egg cells are fertilized by small, non-motile [[sperm]]atia. In [[flowering plant]]s, the gametes are non-motile cells within [[gametophyte]]s.
The form of heterogamy that occurs in [[animal]]s is '''[[oogamy]]'''. In oogamy, a large, non-motile egg cell ([[ovum]]) is fertilized by a small, motile sperm cell ([[spermatozoon]]). The large egg cell is optimized for longevity, whereas the small sperm cell is optimized for motility and speed. The size and resources of the egg cell allow for the production of [[pheromone]]s, which attract the swimming sperm cells.
== See also ==
*[[Gamete]]
*[[Isogamy]]
[[Category:Reproduction]]
[[Category:Germ cells]]
{{cell-biology-stub}}
[[da:Anisogam]]
[[id:Anisogami]]
[[pl:Anizogamia]]
[[sv:Anisogami]]