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a name applied to the endometrium during pregnancy, all of which except for the deepest layer is shed after childbirth; called also decidual or deciduous membranes. adj., adj decid´ual.
basal decidua (decidua basa´lis) that portion lying under the implanted ovum and chorion.
capsular decidua (decidua capsula´ris) that portion directly overlying the implanted ovum and chorion, facing the uterine cavity.
menstrual decidua (decidua menstrua´lis) the hyperemic uterine mucosa shed during menstruation.
parietal decidua (decidua parieta´lis) (true decidua) (decidua ve´ra) the decidua exclusive of the area occupied by the implanted ovum and chorion.
the layer of endometrium overlying the implanted chorionic vesicle; it becomes progressively attenuated as the chorionic vesicle enlarges and, by the fourth month, is squeezed against the decidua parietalis and thereafter undergoes rapid regression.