Plasma Progesterone Levels in Pregnant and Pseudopregnant Ferrets

In the ferret, the life-span and growth of the CL is dependent on pituitary hormones. Hypophysectomy arrests the development of the CL (Hill & Parkes, 1932) and causes regression of well-developed CL in pseudopregnant ferrets. Section of the pituitary stalk, however, does not inhibit the function of the CL during the first half of pseudopregnancy (Donovan, 1963). Since ovariectomy results in abortion (McPhail, 1935; Galil, 1965), any placental progesterone secretion is apparently inadequate to sustain the normal pregnant state. There is little evidence that placental or uterine factors influence the life-span of the CL. When the products of conception are removed 22, 27 or 30 days post coitum, the CL are indistinguishable 8 to 15 days later from those of normal gestation and oestrus recurs normally, about 7