A microangiographic study of the fetal arterial vasculature in the human placenta in uncomplicated pregnancy.

Abstract

Abstract. The fetal arterial vasculature of 36 normal human placentas was studied by microangiography. There are two fairly readily distinguishable types of intracotyledonary artery. The first intracotyledonary artery (type A) is long and narrow and runs straight from the chorionic space towards the decidua. Its branches run within the same stem in the same or the opposite direction. The second intracotyledonary artery (type B) is thicker and twisted, and its branches extend perpendicularly from the stem. According to the distribution of these two types of arteries, three different groups of cotyledons were distinguished—those with only type A arteries, those with only type B arteries, and those with both types of intracotyledonary arteries. In these mixed cotyledons the type B arteries were always situated in the middle of the cotyledon. A fourth cotyledonary group was also distinguished; it was composed of an irregular mixture of different types of arteries, which could often only be classified with difficulty. Recurrent anchoring arteries could definitely be demonstrated. These were always branches of type B intracotyledonary arteries. In 5 of the 36 placentas spiralling involved almost all the fetal placental arteries.