What is a sperm plug?

A sperm plug is a gelatinous substance that is deposited by male animals, including insects, reptiles, and mammals, in the female reproductive tract during copulation. Its main function is to prevent the female from remating with other males, thereby ensuring that the male's sperm will have a higher chance of fertilizing the female's eggs. Sperm plugs are composed of a variety of substances, including proteins, glycoproteins, and polysaccharides, and their composition can vary depending on the species of animal. In some species, the sperm plug can remain in the female reproductive tract for extended periods of time, which may help to ensure the long-term exclusivity of the male's genetic material.