Spermatogenesis is a series of process by which spermatogonia are changed to spermatozoa (sperms). The spermatogenesis is divided into three phases—spermatocytosis, meiosis, and spermiogenesis. In female, the maturation of primitive germ cells to mature gamete is known as oogenesis. Capacitation is the final step of maturation of spermatozoa in the female genital tract in the process of fertilization. It requires 7 hours of time. The zygote formed after fertilization, is very big cell. To restore the normal size of cell, the zygote undergoes repeated cleavage division. Blastocyst is derived from morula by accumulation of fluid inside it. It has two parts—one is trophoblast and other embryoblast. Zona pellucida is a covering, surrounding the secondary oocyte. Notochord, chorion, allantois or allantoenteric diverticulum, gastrulation, different types of placenta, placenta previa, placental barrier, physiological umbilical hernia, nonfusion of müllerian duct, abnormal form or teratology, development of certain important organs (special embryology), etc. are the other important topics which are discussed thoroughly in this chapter.