Immunofluorescence shows localisation of prolactin to human amnion.

TLDR: Using indirect immunofluorescence, localisation of prolactin to the human amnion is reported, indicating a second source of amniotic fluid prolactIn, which differs in molecular size from foetal pituitary Prolactin, suggesting different origins.

Abstract: AMNIOTIC fluid in man and rhesus monkey contains very high concentrations of prolactin1–3, but its origins are unknown. It does not seem to come from the maternal circulation because isotopically labelled prolactin injected into the pregnant rhesus monkey does not appear in amniotic fluid2. One source of prolactin is suggested by the passage of foetal pituitary prolactin through the immature kidney into the urine and then into amniotic fluid4,5. But amniotic fluid and foetal prolactin differ in molecular size, suggesting different origins4. Incubated human amnion and chorion, but not placenta, release prolactin into the medium, indicating a second source of amniotic fluid prolactin2. Using indirect immunofluorescence, we report localisation of prolactin to the human amnion.