Operating within yin and yang, bodily functions could be categorized through systems. In many drawings and diagrams, the twelve channels and their visceral systems were organized by yin and yang, and that organization was identical in female and male bodies. This points to the understanding in traditional Chinese medicine that female and male bodies were no different on the plane of yin and yang. Their gendered differences were not acknowledged in diagrams of the human body. Medical journals were filled with illustrations of male bodies or androgynous bodies, those that did not display gendered characteristics.