abnormal visceral yolk sac morphology excessive folding of visceral yolk sac 2011-06-24T03:39:13Z MP:0011205 MPheno.ontology csmith folded visceral yolk sac ruffled visceral yolk sac the appearance of wrinkles or folds on the surface of the visceral yolk sac visceral yolk sac ruffling wrinkled visceral yolk sac