What is the initial cell produced by the fusion of two gametes during sexual reproduction?

The initial cell produced by the fusion of two gametes during sexual reproduction is known as a zygote. This process starts when a sperm cell from the male fertilizes an egg cell from the female, leading to the formation of a single diploid cell that contains a complete set of chromosomes—half from each parent. The zygote serves as the foundational stage for developing into an organism.

Following the formation of the zygote, it undergoes a series of mitotic divisions, leading to the formation of an embryo. The embryonic stage progresses further into more complex forms, eventually developing into a fetus. However, the terms blastocyst, embryo, and fetus refer to later stages of development following the zygote. Thus, the zygote is precisely the first cell that marks the beginning of a new individual following fertilization.