Degeneration (medical)

Degeneration is deterioration in the medical sense. Generally, it is the change from a higher to a lower form. More specifically, it is the change of tissue to a lower or less functionally active form.
 * True degeneration: when there is actual chemical change of the tissue itself.
 * Infiltration: when the change consists of the deposit of abnormal matter in the tissues
 * Degenerative disease