Involution (medicine)

Involution is the shrinking or return of an

organ to a former size. At a cellular level, involution is characterized by the process of proteolysis of the basement membrane (basal lamina), leading to epithelial regression and apoptosis, with accompanying stromal fibrosis

. The consequent reduction in cell number and reorganization of stromal tissue leads to the reduction in the size of the organ.

Examples

Thymus

The

sex hormones, and chemical or physical castration of an adult results in the thymus increasing in size and activity.^[1]

Uterus

Involution is the process by which the

parturition; the hypertrophy of the uterus has to be undone since it does not need to house the fetus anymore. This process is primarily due to the hormone oxytocin. The completion of this period is defined as when the diameter of the uterus returns to the size it is normally during a woman's menstrual cycle.^{[citation needed}

]