What is the term for a fertilised egg cell?

A fertilised egg cell is known as a zygote. This term specifically refers to the initial cell formed when a sperm cell successfully fertilizes an ovum (egg cell). The zygote contains a complete set of chromosomes, half originating from the sperm and half from the egg, making it diploid, meaning it has two sets of genetic material.

At this early stage, the zygote begins to undergo cell division and development, eventually leading to the formation of an embryo. The terms like "nucleus" refer to the organelle within a cell that contains genetic material but do not describe the fertilised cell itself. A "blastocyst" is a later stage of development following the zygote, where the cell mass has begun to organize and form a cavity, preparing for implantation in the uterine wall. "Gamete" refers to the sex cells (sperm and eggs) prior to fertilization, thus not applicable to the fertilised egg cell.