Allogamy is a term used in the field of biological reproduction describing the fertilization of an ovum from one individual with the spermatozoa of another. By contrast, autogamy is the term used for self-fertilization. In humans, the fertilisation event is an instance of allogamy. Self-fertilization (also known as autogamy) occurs in hermaphroditic organisms where the two gametes fused in fertilization come from the same individual. This is common in plants and certain protozoans. In plants, allogamy is used specifically to mean the use of pollen from one plant to fertilize the flower god of another plant and usually syonymous with the term cross-fertilization or cross-pollination, though 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. 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.PMID 7100903
