arrangement of the ovules in the placenta and of the placentas in the ovary
placentation详细解释
plac.en.ta.tion n.（名词） Formation of a placenta in the uterus.胎盘形成：胎盘在子宫中的形成过程The type or structure of a placenta.胎盘形式或构造Botany Arrangement of placentas within the ovary.【植物学】 胎座式：子房内胎座的组成形状
