. . . Elevated levels of oxytocin have been found in the hypothalamus of male rats (Argiolas 1992) and in the circulation of human males at the time of ejaculation during sexual intercourse, presumably related to orgasm.

A comparable release of the neurohormone in females has been documented (Carmichael et al. 1994) including contractions of muscles in the pelvic floor which accompany orgasm, which is not so easily observed as in males. The neurodynamics that determine intervals between orgasms in multiorgasmic women is no better known than that of the contractions at parturition. . . . Whipple, Ogden and Komisaruk (1992) found that genital stimulation is not essential. Some women can reach orgasm solely by erotic fantasy. In other studies, women who have spinal injury with paralysis and anesthesia below the level of transection develop sexual hypersensitivity of the skin of the chest at or above the level, such that gentle stimulation brings them to orgasm. . . .

Freeman, Walter J., 1995, Societies of Brains: A Study in the Neuroscience of Love and Hate, LEA, INNS Press, 122.