Diagram showing fertilization of egg and sperm Free Vector
Free Vector | Diagram showing fertilization of egg and sperm
The oocyte is normally fertilised in the fallopian tubes, and by the time it reaches the uterus, 5 days later, it has already formed a blastocyst see embryogenesis. Although many sperm can reach the egg, and bind to it, normally ony one sperm fuses with the plasma membrane of the egg, and injects its nucleus. The surface of the egg is covered with fine microvilli, which interact with the sperm, by clustering, and elongating to hold the sperm firmly in position. A protein called fertilin is important in the subsequent fusion of the egg and sperm plasma membranes, but the exact mechanism is still unclear. Polyspermy : occurs if more than one sperm fuses with the egg.
There are many different types of cells in animals. Each type is specialised to do a particular role. These ensure that the organism functions as a whole.
The male and female reproductive gametes sperm and egg have specialised structures which reflect their functions. Video of an Unfertilised Human Egg. Adapted from a video published by the Frisco Institute for Reproductive Medicine. Brent Cornell.