Unsymmetrical dimethylhydrazine (UDMH) (1,1-Dimethylhydrazine) is a hypergolicrocket fuel[?] ingredient, often used in combination with the oxidiser, nitrogen tetroxide.
UDMH is toxic, and can explode in the presence of oxidisers.
... in the male, as a passage for sperm.
The external urethral sphincter is the skeletal muscle that allows voluntary control over urination.
In the human female, ...