gamete

Notably, it’s scientifically inaccurate to say sex can be determined at conception, to say nothing of the limitations of defining a person solely by gamete size.

Helen Gibson, founder of Surrogacy Concern, a UK group which campaigns on issues relating to surrogacy and gamete donation said the organisation did not support "any payment for gametes".

In the process of plant reproduction, when a pollen grain that transports male gametes lands on the stigma of another flower, it initiates the formation of a pollen tube.

This means that the male gametes, which are located at the tip of the pollen tube, cannot fuse with the plant's egg cells.

But as they age, hermaphrodites continue producing eggs and cease producing sperm, leaving them with gametes they cannot self-fertilize.