Various local hypertrophies, including galls, result from the increased growth of young tissues irritated by the punctures of insects, or by the presence of eggs or larvae left behind.
Still further insight is afforded by our increasing knowledge of the enzymes, and it is to be remarked that both poisons and enzymes are very common in just such parasitic Fungi as induce discolorations, hypertrophies and the death of cellse.g.
There are conditions in which we have an abnormal increase in the tissue elements but which strictly should not be defined as hypertrophies, such as new-growths, abnormal enlargements of bones and organs due to syphilis, tuberculosis, osteitis deformans, acromegaly, myxoedema, &c. The enormously long teeth sometimes found in rodents also are not due to hypertrophy, as they are normally endowed with rapid growth to compensate for the constant and rapid attrition which takes place from the opposed teeth.
Second, the right side of the heart (ventricle) hypertrophies (gets more muscular) from the extra exercise demanded of it.
Beyond its normal growth pattern, lymphoid tissue grows excessively (hypertrophies) during an acute infection, as it suddenly increases its immune activity to fight off the invaders.