| Abstract: | Immunoreactive prolactin was measured by RIA in 13.5-15.5 day gestation fetal and 0.5-3.5 day neonatal hamster serum and found to significantly reflect rises and falls in maternal levels. On the average, fetal and neonatal levels were 37% of maternal prolactin serum levels. 125I-PRL injected into 13.5-15.5 day pregnant hamsters was demonstrated to cross the placenta and enter fetal circulation. Ten min after injection, fetal serum levels were calculated to be an average of 3.9% of the radioactivity recorded in maternal serum. There is a strong possibility that fetal prolactin serum levels may be, at least in part, attributed to a maternal source. |
