The female reproductive system is the internal and external organs involved in fertility ... sperm (cells produced by the male reproductive system) must travel through the vagina and into the ...

All mammals have a particular protein on the surface of sperm called CatSper. It controls the entry of the particles needed to power the hyperactive movements in the tail-like flagella that propels ...

Male and female reproductive systems allow ... In humans, conception begins when a sperm fertilises an egg. In female reproductive organs, ovaries produce the eggs and the hormones that regulate ...

They determine the biological sex, reproductive organs ... Most people are born with either male or female sex organs. In rare cases, individuals may be born with ambiguous sex organs, falling ...

This species is simultaneously hermaphroditic, having male and female reproductive organs ... by observing its internal and external reproductive organs. Following this, he raised some individuals ...