abnormal placenta morphology abnormal placenta labyrinth morphology MP:0001716 MPheno.ontology abnormal labyrinth layer morphology abnormal placenta labyrinthine zone morphology abnormal placental labyrinth morphology any structural anomaly of the placental layers where embryonic blood vessels are surrounded by trophoblast cells and maternal blood, and is the site where the exchange of nutrients and waste products occurs between the maternal and fetal circulation