[Venous outflow from the intervillous microcirculation in the human placenta].

This paper presents a morphological description of the venous area of the maternal circulation in the mature placenta. By injection of contrast medium into adjoining fetal cotyledons in 24 placentas the common intercotyledonal venous blood outflow pathways were specifically demonstrated, both radiologically and histologically. The interweaving and density of the terminal villi, the number and location of nuclear bridge formations, the width and course of the intervillous spaces, and the form of the columns and vela are characteristic of the venous outflow areas. The calcium incrustations found in varying degrees are likewise closely associated with venous area of the intervillous microcirculation. The findings are interpreted with regard to their importance for understanding the maternal placental blood flow in relation to the flow unit of the so called placenton.