Fig. 4From: Three-dimensional ultrasonographic features of diamniotic conjoined twins with body stalk anomalyDrawing of the embryogenetic model to explain our case. The common body stalk and single allantois contrast with the separated body stalk and two allantoises of other embryogenetic models. A, allantois; AC, amniotic cavity; BS, body stalk; CM, cloacal membrane; ED, embryonic disk; YS, yolk sacBack to article page