During male-female sexual intercourse, when the man reaches orgasm and ejaculates, the sperm is ejected from the body into the woman’s vagina. The sperm that enters the woman’s vagina travels along the vagina and combines with the egg produced by the woman in the uterus to form an embryo. The fertilized embryo that forms can be deposited in the endometrium on the wall of the woman’s uterus, that is, the fertilized fertilized egg grows on the inner wall of the woman’s uterus, and an embryo is formed. Over time this embryo grows larger and larger over time, eventually forming a fetus, which is called intracorporeal fertilization, which is the opposite of extracorporeal fertilization.