Oestrogen sulphatase activity in endometrium and foetal membranes of late gestational and parturient cows

To estimate oestrogen-sulphatase activity in bovine non-caruncular endometrium, allanto-chorion, allanto-amnion and intact placentomes (designated as placenta), homogenates of these tissues were incubated, using oestrone sulphate as a substrate. Tissues had been collected from two different groups of animals: during laparotomy in cows on Day 262 of gestation (n = 6), and during caesarean section in parturient cows (n = 6). Sulphatase activity was detected in endometrium, allanto-chorion and placenta, but not in the allantoamnion. Placental tissue showed a substantially higher conversion rate than the endometrium. Only in the placenta from parturient animals was sulphatase activity significantly higher than in placentomes obtained on Day 262. It was concluded that in the pregnant cow not only the placenta, but also non-caruncular endometrium and allanto-chorion have the capability to deconjugate oestrogens, and that an increased sulphatase activity in the placenta at parturition might contribute to the parturient rise of free oestrogens in maternal blood.