Gestational changes in prostaglandin production by ovine fetal trophoblast cells

The effect of gestational age on the synthesis of prostaglandins (PG) by isolated preparations of uninucleate and binucleate cells of the ovine placentome has been investigated. PG synthesis by the cells was dependent upon cell number in a linear manner, and was significantly inhibited by indomethacin, but not affected by the addition of exogenous arachidonic acid. The net output of PG by the cells increased progressively with increasing gestational age of the ewe from 35 to 145 days, particularly after 100 days' gestation. The cells prepared from tissue obtained during the last trimester of pregnancy have the ability to produce PGE2 and PGF2 alpha in approximately equal amounts, and a lower synthetic capacity for 6-keto PGF2 alpha. The cells also have the capacity to metabolize PGF2 alpha to 13,14-dehydro, 15-keto PGF2 alpha. Thus the fetal trophoblast cells appear to be the major site of PG production by the placenta at parturition.