the female Clitoris
The clitoris -- which in full, internal and external, is nearly of the same size as the penis -- is usually the most sensitive spot on, and involved in the most sensitive areas of, the vulva
. It's got twice the number of sensory nerve endings the penis does,
and it also interacts with over 15,000 nerve endings throughout the whole pelvic area.
It is created of the same sort of erectile tissue that the head of a penis has
http://www.scarleteen.com/article/bodies/innies_outies_the_vagina_clitoris_uterus_and_more