Allogamy
Allogamy or cross-fertilization is the fertilization of an ovum from one individual with the spermatozoa of another.[1][2] By contrast, autogamy is the term used for self-fertilization.[1] In humans, the fertilization event is an instance of allogamy. Self-fertilization occurs in hermaphroditic organisms where the two gametes fused in fertilization come from the same individual.[3] This is common in plants (see Sexual reproduction in plants) and certain protozoans.[4][5]
In plants, allogamy is used specifically to mean the use of pollen from one plant to fertilize the flower of another plant and usually synonymous with the term "cross-fertilization" or "cross-pollination" (outcrossing).[4] The latter term can be used more specifically to mean pollen exchange between different plant strains or even different plant species (where the term cross-hybridization can be used) rather than simply between different individuals.[6]
Parasites having complex life cycles can pass through alternate stages of allogamous and autogamous reproduction, and the description of a hitherto unknown allogamous stage can be a significant finding with implications for human disease.[7]