The changes in luteal function during pregnancy and pseudopregnancy in the ferret have previously been assessed by the study of the morphology of the ovaries and uterine tract (Hammond & Marshall, 1930; Donovan, 1967) but, with the development of competitive protein-binding techniques, the measurement of progesterone in small quantities of blood has become possible. We have used this procedure to assess progestin secretion by ovarian tissue in anoestrous, oestrous and pseudopregnant ferrets, and also after hypophysectomy.
Blood samples (2 ml), withdrawn by cardiac puncture under Nembutal anaesthesia, were centrifuged as soon as possible after collection and the plasma was stored at −20° C until assay. Plasma progestin concentrations were measured in 0·1-ml aliquots in triplicate as described previously (Blatchley, Donovan, Horton & Poyser, 1972), the limit of sensitivity being 0·8
