“…Although the reason for failure of birth by lesion of the SCN is not clear, large lesions of the hypothalamus may be the cause (Honma et ai, 1984). Parturition in the rat is brought about by intricate mechanisms (Fuchs, 1973;Thorburn & Challis, 1979) involving adrenal function (Bosc & Nicolle, 1979, 1980, pituitary hormones (Fuchs et ai, 1974;Gordon & Sherwood, 1985), relaxin , prostaglandins (Dukes et ai, 1974;Labhsetwar & Watson, 1974;Strauss et ai, 1975;Buckle & Nathanielsz, 1975), ovarian steroids (Cátala & Deis, 1973;Thorburn & Challis, 1979), or relation¬ ship between fetus and mother (Sherwood et ai, 1985). The mechanism affected by lesion of the SCN is uncertain.…”