VASCULAR ENDOTHELIAL GROWTH-FACTOR GENE-EXPRESSION IN OVINE PLACENTA AND FETAL MEMBRANES

OBJECTIVE: The purpose of this study was to explore the gene expressio n of vascular endothelial growth factor (VEGF) in placental cotyledon, chorion, and amnion of the ovine fetus. STUDY DESIGN: Time-dated preg nant sheep with singleton or twin fetuses at a gestational age ranging from 100 to 140 days were used for the study. Placental cotyledonary, chorionic, and amniotic tissues were collected and processed for mess enger ribonucleic acid analysis by Northern blotting and reverse trans cription-polymerase chain reaction. RESULTS: By use of a phosphorus 32 -labeled human VEGF complementary deoxyribonucleic acid probe, a promi nent VEGF messenger ribonucleic acid transcript of 3.7 kb was detected in the cotyledon, chorion, and amnion, A minor band of 1.7 kb was als o found but only in the cotyledon and chorion, The abundance of messen ger ribonucleic acid encoding VEGF was highest (p < 0.001) in the coty ledon and lowest in the amnion. In these tissues polymerase chain reac tion - amplified products corresponding to VEGF(121), VEGF(165), VEGF( 189), and VEGF(206) were identified by ethidium bromide. In addition, a polymerase chain reaction fragment corresponding to VEGF(145) was ob served. These fragments produced specific hybridization signals with t he human VEGF radioactive probe where the intensity of the signal was strongest for VEGF(165) and weakest for VEGF(189). CONCLUSIONS: VEGF g ene expression was detected in the cotyledon, chorion, and amnion of t he near-term ovine fetus. These findings suggest that vascular endothe lial growth factor may play a role in the induction of angiogenesis an d promotion of permeability in the microvessels that perfuse the place ntal and fetal membranes.