isogámi

Isogamy is a form of sexual reproduction found in some organisms where the gametes involved are morphologically indistinguishable. This means that both the male and female gametes, sperm and egg respectively, are the same size and shape. In contrast, anisogamy, or heterogamy, involves gametes of different sizes, with the female gamete typically being larger and less motile than the smaller, motile male gamete. Oogamy is a specialized form of anisogamy where the female gamete is a non-motile ovum and the male gamete is a motile sperm.

Isogamy is observed in various organisms, including certain algae, fungi, and protozoa. In these cases, any two compatible individuals can produce gametes that fuse to form a zygote. The fusion of isogamous gametes results in a zygote that develops into a new individual. While the gametes are morphologically identical, there are often physiological or genetic differences that determine compatibility for fusion. This form of reproduction is considered evolutionarily simpler than anisogamy, as it does not require the development of distinct male and female gamete types. The transition from isogamy to anisogamy is thought to have been a significant step in the evolution of sexual reproduction, allowing for greater specialization and potentially more efficient fertilization.