Correct answer: Egg and sperm
Oogamy is a type of reproduction in which the female gamete is larger than the male gamete. The Oogamous organism is that type of organism who is reproduced by the oogamy form of reproduction. In these type of organism, the female gamete is bigger than the male gamete. It is a form of heterogamy, which is a type of sexual reproduction in which the gametes differ in size and form.
Hence, the given blanks can be filled with 'egg and sperm' respectively.