abnormal placenta morphology abnormal placenta 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 MP:0001716 abnormal placental labyrinth morphology abnormal placenta labyrinthine zone morphology abnormal labyrinth layer morphology MPheno.ontology