involution /in′vəlo̅o̅″shən/ [L, involvere, to wrap up] , 1. a normal process of turning or rolling inward characterized by a decrease in the size of an organ caused by a decrease in the size of its cells, as in postpartum involution of the uterus. 2. (in embryology) a developmental process in which a group of cells grows over the rim at the border of the organ or part and, rolling inward, rejoins the organ or part to form a tube, such as in the heart or bladder.
