Pathology of the Endocrine System

The endocrine system represents multiple cell signaling systems that regulate metabolic processes and maintain body homeostasis in the fetus and adult. The endocrine system regulates many biologic processes including development, growth, reproduction, gastrointestinal, cardiovascular, and renal systems, among others, as well as the response of the body to acute and chronic stress. Anatomically, the endocrine glands are distinct collections of specialized cells that respond to both internal and external environmental signals and produce and secrete chemical mediators or hormones, which generally fall into three categories: polypeptides, steroids, and tyrosine derivatives. Regulation of the endocrine glands is the result of both positive and negative feedback loops, which allow for both rapid and sustained changes in hormone production and secretion. Xenobiotics and environmental compounds have the potential to perturb the function of endocrine organs. Toxic effects of xenobiotics on the endocrine organs can result from either the stimulation or inhibition of hormone production and secretion. The proliferative lesions may be functional or nonfunctional. Gross and microscopic histopathology is used to identify proliferative lesions in the endocrine glands. In this chapter, we examine the main endocrine organs: pituitary gland, thyroid and parathyroid gland, adrenal gland, endocrine pancreas, and the pineal gland. Functional anatomy and physiology, spontaneous or background lesions, and xenobiotic-related proliferative and nonproliferative lesions for each organ are discussed.