SERUM LEVELS OF PROLACTIN DURING THE OVARIAN CYCLE, PREGNANCY, AND LACTATION IN THE COMMON MARMOSET (CALLITHRIX-JACCHUS)

A homologous double-antibody radioimmunoassay developed for humans was used to measure serum prolactin, progesterone, and estradiol in commo n marmosets. In the ovarian cycle of common marmosets, serum progester one began to increase after an estradiol surge, attained a peak level, and then declined before the ensuing pre-ovulatory rise in estradiol. During the luteal phase, the change in serum concentrations of estrad iol was synchronized with that of progesterone. During the ovarian cyc le there was no consistent change in serum prolactin concentrations. D uring the last 75 days of pregnancy the prolactin level was higher tha n during the ovarian cycle and the first 70 days of pregnancy. Moreove r, during lactation, mothers with suckling twin infants had a higher p rolactin level than during the final stage of pregnancy.