Ontogeny of aquaporins 1 and 3 in ovine placenta and fetal membranes

A sensitive and highly reproducible method has been used to shaw that Aquap orin 3 (AQP(3)) mRNA is present in the ovine placenta and chorion from at l east 60 days of gestation (term=145-150d) with levels increasing substantia lly (>16 fold) at 100 days, and remaining constant thereafter. By immuno- a nd hybridization histochemistry, the epithelial cells expressing AQP(3) wer e found to be the trophoblast cells. Some AQP(3) was expressed in fibroblas ts of the amnion and allantois but none was expressed in the epithelia of t hese membranes. AQP(1) was expressed in endothelial cells of fetal and mate rnal blood vessels but not in any epithelial cell of the ovine placenta and fetal membranes. The level of AQP(3) expression is consistent with known o vine placental permeabilities to water, glycerol and urea. (C) 2000 Harcour t Publishers Ltd.