Some of the mudras like the maha-mudra have to be used in combination with other techniques in order for them to work: pranayama, visualisation and bandhas are often mentioned. So often the mudras are hybrid techniques combining a range of limbs.
Other mudras are not body poses at all. They seem to derive from various unrelated discourses and practices. This group of mudras could rather be described as Tantric rituals -many probably descending from the Kula tradition. One mudra – the khechari – for instance is about extending the tongue by slowly cutting it half-loose and then swallowing it. That will stop the bindu from dripping and secure immortality and perfection320. Others are about inverting semen (vajroli-mudra), or having sex and then inverting semen, or after having sex smearing the body with cow dung, ashes and semen (sahajoli-mudra). Finally, the amaroli mudra is about drinking urine.
Hops Humulus lupulus, traditionally used to brew beer, bind Ardha Matsyendrasana Yoga Pose to estrogen receptors in vitro but do not stimulate uterine growth in ovariectomized rats Beckham, 1995 Ardha Matsyendrasana Yoga Pose ; Fackleman, 1998. Hops strobiles contain estrogenic prenylflavanone, 8-prenylnaringenin 8-PN, 6-prenylnaringenin 6-PN, isoxanthohumol IX, and xanthohumol XN. The effects of hops on P450 enzyme systems tend not to be clinically significant because the enzymes inhibited by hops are not relevant to most medications Henderson, Miranda, Stevens, Deinzer, & Buhler, 2000. Extracts of hops and red clover, genistein and 8-PN, activate the estrogen response element ERE in Ishikawa cells while extracts, biochanin A, genistein, and 8-PN induced ERE-luciferase expression in MCF-7 cells. Hops and red clover extracts as well as 8-PN upregulated progesterone receptor PR messenger RNA in the Ishikawa cell line. In the MCF-7 cell line, PR messenger RNA was significantly upregulated by the extracts biochanin A, genistein, 8-PN, and IX. Further research on hops and red clover may be of value for treatment of menopausal symptoms Overk et al.