Studies on the Muscular Physiology of the Genital Tract

Abstract

Summary.Surviving vagina from rats with a normal sexual cycle often exhibits a moderate degree of spontaneous activity in metoestrus. In the other sexual phases this activity occurs only exceptionally and very weakly. Vagina from castrates invariably develops a lively spontaneous activity with high contraction frequency and great amplitude. This can be dampened or inhibited by pre‐treating the castrated animal with oestrin.From this the conclusion is drawn that the vagina possesses an inherent spontaneous muscular activity that is dampened through the influence of the oestrin.Vaginal muscle from rats with a normal sexual cycle is positively adrenotropic in all sexual phases, vaginal muscle from castrates is negatively adrenotropic. The negative reaction to adrenaline shown by the vagina of castrates can be converted into positive by p re‐treatment of the castrate with oestrin.The amplitude of the adrenaline contraction is smaller in pro‐oestrus than in the other sexual phases. This is in all probability owing to the fact that the tonus of the vaginal musculature is highest in the heat phase. This assumption is strongly supported by certain observations made on living, unaesthetized animals.Vaginal muscle from rats with a normal sexual cycle is refractory to oxytocin in all sexual phases. Vaginal muscle from castrates responds to oxytocin by an increase in tonus and contraction frequency. This effect is inhibited if the castrated animal is pre‐treated with oestrin.