DOPPLER EVIDENCE OF INTERVILLOUS FLOW IN THE EMBRYONIC PERIOD

The characterization of the nature and time of onset of intervillous b lood flow has been the subject of much recent debate. This review adva nces several hypotheses regarding the physiology of intervillous flow and summarizes the human and monkey evidence that currently exists. As foundational to the discussion, the historical light microscopic data is presented, and this is then coupled with illustrations from curren t ultrasound work that involves pulsed wave Doppler, color amplitude i maging, and color Doppler imaging, The evidence clearly suggests that intervillous flow is a normal and consistent finding in the early firs t trimester pregnancy.