ABSTRACT
The endocrine system is made up of a series of glands that produce hormones, substances that regulate different functions in the body. This chapter describes the histological structure of the hypophysis (pituitary gland), thyroid gland, parathyroid gland, adrenal gland, and epiphysis (pineal gland). For each of them, reference is made to their main clinical correlates. In the final part of the chapter, the differences between these glands in birds, reptiles, amphibians, and fish are described.
