What are the male and female reproductive organs in animals release (A) that fuse together to form (B)?

The male and female reproductive organs are the testes and ovaries respectively that releases male and female gametes. Whereas the male(sperm) and the female(ovum) fuse together to form a zygote. 

In the embryonic development of humans and other animals, the zygote stage is brief and is followed by cleavage, when the single cell becomes subdivided into smaller cells.