During fertilization, what occurs after a sperm successfully penetrates the egg?

After a sperm successfully penetrates the egg, the fertilized egg undergoes mitosis, which is the process of cell division. This occurs as soon as the sperm and egg nuclei fuse, resulting in a diploid zygote. Following fertilization, the zygote begins a series of cell divisions, which leads to the formation of an embryo as it travels down the fallopian tube toward the uterus.

This series of mitotic divisions is crucial for the development of the embryo and eventually implanting it into the uterine lining for further growth. The process of mitosis ensures that the genetic material is replicated and distributed properly as the zygote starts to develop into a multicellular organism.

In contrast, other options do not accurately represent what happens immediately after fertilization. The egg is not expelled from the uterus; hormones for ovulation are not released during this phase; and there is no rejection of sperm by the female body at this stage, as sperm has already successfully penetrated the egg. Thus, the initiation of mitosis after fertilization is the correct response, highlighting the beginning of embryonic development.