What is the product of fertilization between an egg and a sperm cell?

The product of fertilization between an egg and a sperm cell is a zygote. This stage marks the very first cell that is formed when the genetic material from both the egg and sperm unite. The zygote contains a complete set of chromosomes, half from the mother and half from the father, establishing the genetic blueprint for the new organism.

After fertilization, the zygote begins a series of cell divisions, a process known as cleavage, and eventually develops into an embryo. An embryo represents the subsequent stage in development after the zygote begins to divide and differentiate into various cell types. A fetus refers to a later stage in development, typically after the first few weeks of embryonic growth when the basic structures of the organism have been established.

In summary, the zygote is the initial product of fertilization, which is foundational for all subsequent stages of development, including the embryo and fetus.