The observations summarized above are in line with the concept of epigenetically inherited phenotypes. In-depth investigations will be needed to provide insights about gene regulatory mechanisms underlying the transmission of cannabis effects through the germline and how they relate to sex. The endocannabinoid system plays important roles not only in the development of the cells and physiological systems of the brain, but also in reproduction. It is known that both male and female reproductive tissues express CB receptors and endocannabinoid ligands, and that in males THC can disrupt gonadal functions (Banerjee et al., 2011; Bari et al., 2011). Studies on the impact of cannabinoids on epigenetic changes in male fertility have been conducted in Cnr1 null mutant mice that displayed abnormal histone retention in germ cells compared to wild type mice (Chioccarelli et al., 2010). In that study, Cnr1 expression was demonstrated to be necessary for spermiogenesis by controlling chromatin condensation, resulting in poor sperm quality. Adverse effects of cannabis exposure on the ovary of females have also been found to present a higher risk of infertility due to anovulation
