Location of the angiogenic activity in the pregnant human uterus

Angiogenic activity was known to be intensely dynamic during pregnancy with a geometric orientation towards the site of implantation. Therefore this study was designed to test whether the uterine lining of pregnancy, the decidua, induces angiogenic activity on the chorioallantoic membrane (CAM). Twenty-three decidual specimens obtained during legally induced abortions were implanted into the 9-day-old chick CAM. All decidual specimens showed strong angiogenic activity as measured by 9-fold increase in radial blood vessels, with a geometrical formation of 'spokewheel' pattern extending over a range of 1.2 cm within 48 h.