[Histopathogenesis of goiters]

The basic mechanisms acting in the transformation of a normal thyroid gland into a toxic or nontoxic goiter are summarized: 1) Any goiter arises from multiplication of follicular epithelial cells forming new follicles. 2) In the follicular epithelium there are cell families with much higher than average growth potential. 3) Cells of an individual follicle are not identical but heterogeneous. 4) Each follicular cell has a certain level of autonomy of growth and of function.