PROTEIN AND STEROID-LEVELS IN EMBRYONIC CAVITIES IN EARLY HUMAN-PREGNANCY

Biochemical analysis including concentrations of urea, creatinine, hum an chorionic gonadotrophin (HCG), oestradiol, progesterone, and alpha- fetoprotein (AFP), two-dimensional gel electrophoresis, and the affini ty of AFP for Concanavalin A (Con A)-Sepharose were performed on sampl es of exocoelomic and amniotic fluids retrieved by transvaginal punctu re and maternal serum from 25 normal pregnancies between 5 and 12 week s of gestation. Biochemical assays showed that during this period of g estation no differences in urea concentration were found between fluid s from the three compartments, whereas creatinine concentration decrea sed significantly (P < 0.001) from maternal serum to amniotic fluid. T he exocoelomic fluid contained significantly (P < 0.001) higher concen trations of oestradiol, progesterone and HCG than both maternal serum and amniotic fluid. AFP concentration was similar in amniotic and exoc oelomic fluids and significantly (P < 0.001) lower in maternal serum. Between the second and the third months of gestation, urea concentrati on decreased significantly (P < 0.05) and oestradiol, HCG and AFP incr eased significantly in maternal serum (P < 0.05, P < 0.05, P < 0.001, respectively). During the same period of gestation, exocoelomic fluid concentrations of urea and HCG decreased significantly (P < 0.005, P < 0.001, respectively). Comparison of the two-dimensional gel patterns obtained from maternal serum with those from exocoelomic amniotic flui ds revealed no significant qualitative differences, except for several small proteins. These results suggest that protein pathways across ma terno-embryonic membranes are not simply passive transfers. Con A affi nity molecular variants of AFP demonstrated that both exocoelomic and amniotic fluid AFP were mainly of yolk sac origin and that maternal se rum AFP was mainly of fetal liver origin, suggesting that the human se condary yolk sac has both absorptive and excretory functions.