The Histology of Endocrine Glands

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The Histology of Endocrine Glands Dr. Tatiana Jones, MD, PhD NCC Hypophysis (Pituitary Gland) It is a collection of different cell types that control the activity of other endocrine organs. The pituitary is divided into the darker staining anterior pituitary and lighter staining posterior pituitary. The posterior pituitary is connected to the hypothalamus by the pituitary stalk. The stalk contains axons of neurons whose cell bodies reside in the hypothalamus and that release their hormones in the posterior pituitary. The Posterior Pituitary (Neurohypophysis) Derived from the hypothalamus. Composed of unmyelinated axonal processes (cell bodies reside in the hypothalamus). The neurons release the releasing hormones, as well as oxytocin and vasopressin (ADH). The pituitary stalk connects the hypothalamus and pituitary. The posterior pituitary also has characteristic Herring bodies, which are focal axonal swellings packed with secretory granules. Most of the cells visible in the slide belong to supporting cells, pituicytes, the glial cells of the pituitary gland. The Anterior Pituitary (Adenohypophysis) The anterior pituitary is also known as the adenohypophysis. It contains cells that, when stained by H&E, appear as acidophils, basophils, or chromophobes. Cells of Adenohypophysis The Thyroid Gland Isthmus Right Left lobe lobe Calcitonin T4 or Thyroxine T3 or Triiodothyronine The Parathyroid Gland Chief (principal) cells, which have prominent central nuclei surrounded by pale cytoplasm. Chief cells produce parathyroid hormone (PTH), which is the most important regulator of calcium metabolism in humans. When serum calcium levels fall, chief cells release PTH which indirectly stimulates the production of osteoclasts in bone. Oxyphilic cells, which are large and fewer in number, have small, dark nuclei and an acidophilic cytoplasm with many mitochondria. The function of these cells is unknown, but they increase in abundance as a person ages. Adrenal or Suprarenal Glands Medulla (It is considered part of Sympathetic Autonomic nervous System) Catecholamines (Epinephrine and Norepinephrine) Sex hormones ( androgens) Glucocorticoids (Cortisol, Cortisone and Corticosterone) Mineralocorticoids (Aldosterone) The Pancreas Endocrine pancreas Exocrine pancreas Islets of Langerhans Pancreatic acini 1- Beta cells: Insulin They secrete large quantities of an alkaline, enzyme rich fluid 2- Alpha cells: Glucagon 3- Delta cells: Somatostatin 4- F cells: Pancreatic polypeptide.

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Histochemical Characterization and Functional Significance of the Hyperintense Signal on MR Images of the Posterior Pituitary
1079 Histochemical Characterization and Functional Significance of the Hyperintense Signal on MR Images of the Posterior Pituitary 1 John Kucharczyk ,2 MR imaging of the pituitary fossa characteristically shows a well-circumscribed area Walter Kucharczyk3 of high signal intensity in the posterior lobe on T1-weighted images. We used a Isabelle Berri,4 combination of high-field MR, electron microscopy, and histologic techniques in experi Jack de GroatS mental animals to determine whether the hyperintensity of the posterior lobe might be William Kelly6 functionally related to hormone neurosecretory processes, and to attempt to establish its chemical nature. Histologic sections of a dog's pituitary gland processed with lipid David Norman 1 1 specific markers showed intense staining in the posterior lobe but not in the anterior T. H. Newton lobe, thus documenting the location of fat in the posterior pituitary. Administration of vasoactive drugs known to influence vasopressin secretion to anesthetized cats pro duced changes in the volume of high-intensity signal in the posterior pituitary. Subse quent electron microscopy showed a significant increase in posterior lobe glial cell lipid droplets and neurosecretory granules in dehydration-stimulated cats. The data suggest that the pituitary hyperintensity represents intracellular lipid signal in the glial cell pituicytes of the posterior lobe or neurosecretory granules containing vasopressin. The volume of the signal may, in turn, reflect the functional state of hormonal release from the neurohypophysis. While CT and MR imaging can both be used to evaluate patients with suspected pituitary disease, high-field high-resolution MR imaging is increasingly the method of choice [1-3].
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The Preoptico-Hypophysial Neurosecretory
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Histology of the Pituitary Gland and Endocrine System Notes 1 Lecture notes: Histology of the Pituitary Gland and Endocrine System 1. Describe the structural organization of endocrine glands 2. Define the components of the endocrine system 3. Compare and contrast the cellular composition of the adenohypophysis (anterior pituitary) and neurohypophysis (posterior pituitary gland) 4. Describe the hypophyseal portal system and its physiological significance 5. Compare and contrast the cellular composition of the adrenal cortex and adrenal medulla 6. Describe the organization and cellular features of the thyroid gland and parathyroid glands and the hormones their cells produce 7. Explain the structural features and functions of the pineal gland 8. Bone as an endocrine organ 9. Define the diffuse neuro-endocrine system Histology of the Pituitary Gland and Endocrine System Notes 2 HISTOLOGY OF ENDOCRINE GLANDS 1. Describe the structural organization of endocrine glands The endocrine system is a collection of glands that secrete hormones, molecules that transmit chemical messages. Hormones are capillary released to the bloodstream and act secretory c on cells that express the appropriate receptor in target organs. Endocrine cells are typically composed of islands endocrine gland exocrine gland of secretory cells of epithelial origin that discharge their products into capillaries, unlike the cells of exocrine glands that release their products into an epithelial duct. Based on their chemical structure, hormones can be classified as: • proteins and glycoproteins • small peptides • amino-acid derivatives • steroids Types of secretion Endocrine secretion: the cell content is released to the circulation on the basolateral membrane, through a basement membrane that separates the endocrine cells from the blood stream.
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