Fusion of two gametes unequal in size or form; fertilization as distinguished from isogamy or conjugation. [aniso- + G. gamos, marriage]
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an·isog·a·my (an″i-sogґə-me) [aniso- + Gr. gamos marriage] in the most restrictive sense, fertilization of a large motile female gamete by a small motile male gamete; the term is often used more generally to mean the sexual union of two dissimilar gametes (heterogamy), particularly in lower organisms.Medical dictionary. 2011.