Implantation is the attachment of blastocytes to the uterine wall. Gametes. The major reproductive events in human beings are as follows$(i)$ Gametogenesis It is the formation of gametes. It includes spermatogenesis (formation of sperms) and oogenesis (formation of ova/eggs)$(ii)$ Insemination It is the transfer of sperms by the male into the genital tract of the female$(iii)$ Fertilization Fusion of male and female gametes to form zygote is called fertilization$(iii)$ Fertilization Fusion of male and female gametes to form zygote is called fertilization$(iv)$ Cleavage It is rapid mitotic divisions of the zygote which convert the single celled zygote into a multicellular structure called blastocyst (blastula)$(v)$ Implantation It is the attachment of blastocyst to the uterine wall$(vi)$ Placentation It involves the formation of placenta which is the intimate connection between the foetus and uterine wall of the mother to exchange the materials$(vii)$ Gastrulation It is the process by which blastocyst is changed into gastrula with three primary germ layers$(viii)$ Organogenesis It is the formation of specific tissue, organs and organ systems from three primary germ layers$(ix)$ Parturition (child birth) it involves expelling of the baby from the mother's womb (uterus)