What is the term for the cell formed immediately after fertilization?

The term for the cell formed immediately after fertilization is referred to as the zygote. When a sperm cell successfully fertilizes an egg cell, the resulting single cell is called a zygote. This zygote contains a complete set of genetic material from both parents and is the first step in the process of developing into an organism. Following fertilization, the zygote will begin to divide and develop into a multi-cellular structure, leading eventually to the formation of an embryo.

The other terms listed represent different stages or components of reproduction. A blastocyst develops later in the process of embryonic development after the zygote has undergone several rounds of division and is about to implant in the uterine wall. An embryo refers to the stage following the zygote, which occurs once implantation happens and development begins. A gamete pertains to the reproductive cells—sperm and egg—that combine during fertilization to form the zygote.