Anizogámia

Anizogámia, also known as heterogámia, is a form of sexual reproduction in which the gametes (sex cells) are morphologically dissimilar. This means that the male and female gametes differ in size and/or structure. Typically, the female gamete, the ovum or egg, is larger and non-motile, containing stored nutrients. The male gamete, the sperm or spermatozoon, is smaller and motile, specialized for reaching and fertilizing the ovum.

This difference in gamete size is a fundamental distinction from isogámia, where gametes are morphologically identical. Anizogámia is the most common form of sexual reproduction in multicellular organisms, including animals, plants, and fungi. The evolutionary advantage of anizogámia is thought to lie in the specialization of each gamete. The large, nutrient-rich ovum provides resources for the developing embryo, while the small, motile sperm efficiently seeks out the ovum.

The fusion of an ovum and a sperm results in a zygote, which then develops into a new organism. The genetic material from both gametes combines, leading to genetic diversity within a population, a crucial factor for adaptation and evolution. The production of anisogamous gametes is often regulated by distinct reproductive organs and processes within an organism.