Essence chamber

1. Life gate. The Classic of Difficult Issues (难经 nàn jīng, 36) states, The life gate is the abode of essence and spirit and to which source qì is connected. In the male, it stores essence; in the female, it ties [around] the uterus.

2. Also house of essence; palace of essence. Specifically (and more commonly), the place where semen is stored.