Histology of three endocrine glands Anatomy and Physiology Lab II Fall 2017 Dr. Santos

Thyroid gland Composed of hollow spheres called thyroid follicles The cells that line the follicles are simple cuboidal cells called follicle cells, they surround a gelatinous, iodine rich substance called colloid. In between the follicles, we find C cells or parafollical cells. These cells secrete calcitonin, which regulates calcium metabolism.

Adrenal glands Sit atop the superior pole of each kidney. 2 separate glands! The superficial region called the adrenal cortex secretes steroid hormones in response to stimulation by ACTH (adrenocorticotropic hormone) and other factors.

Adrenal gland The adrenal cortex has three zones; Zona glomerulosa- outer thin layer where the cells are arranged in clusters. Secretes mineralocorticoids, such as aldosterone, that regulates fluid and electrolyte homeostasis. Zona fasciculata- middle layer where cells are stacked on top of each other and resemble columns. Secretes steroids such as glucocorticoids, such as cortisol, regulates stress response, blood glucose, fluid homeostasis, and inflammation. Zona reticularis- inner layer where the cells are stain darkly and are more tightly packed. Secretes gonadocorticoids that affect the gonads and other tissues.

The adrenal medulla- has numerous, loosely arranged blood vessels.

The adrenal medulla Consists of modified postsynaptic sympathetic neurons that secrete epinephrine and norepinephrine in response to sympathetic stimulation. “fight or flight reaction”

Pancreas histology Has both exocrine and endocrine function Acinar cells- exocrine portion “Pancreatic islands”- insulin and glucagon secreting cells