Answer: 1,3,4
Involution is simply the transition or change of form and size of an organ from its newer size to its previous or initial size. This phenomenon is often observed at the cellular level of life and occurs as a result of the proteolysis of membranes in the lowest levels.
Epithelial regression subsequently takes place during the process of involution. The waste-product of this organ “shrink” is called stromal fibrosis