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PDFaid.Com #1 Pdf Solutions nd oc rin e1 M D C U Morphology of Major Endocrine Glands Amornpun Sereemaspun M.D., Ph.D. Depicha Jindatip Ph.D. Department of Anatomy, Faculty of Medicine Chulalongkorn University M D C U Topics to be discussed and studied Endocrine Gland nd Organization e1 Clinical Relevance Microscopic oc Gross Structure Function rin Structure Cell Structure/Fn. Intracellular organelles U C M D nd oc rin e1 PART I : Endocrine & Concept of Cell Communications e1 M D C U Intercellular communication rin • Communication between cells oc – Direct electrical coupling • Synaptic or anatomical junction nd – Chemical substances • hormones or neurotransmitters C U Homeostasis & Endocrine M D Homeostasis e1 (physiological state in which the physical and chemical conditions of the internal environment are being maintained) oc rin Most organ systems contribute to homeostasis nd Nervous System Endocrine System Electrical Means of communication (±chemical) nd C e1 Chemical reacts slower continue ~ weeks adapts quickly and response declines more persistent responses targeted and specific widespread effects on many organs oc Adaptation to long-term stimuli Area of effect reacts faster stops quicker rin Speed and persistence of response Endocrine Systems M D Nervous Systems U Endocrine vs. Nervous System C U Vertebrate Hormones Functions nd oc rin e1 M D Control … U Chemical Hormone Groups • secreted by adrenal cortex, ovary, testis • molting hormone of insects Steroid hormones rin e1 Fatty acid derivative M D C • Prostaglandins • juvenile hormone of insects oc Amino acid derivatives nd • thyroid hormones • epinephrine Peptides and proteins • antidiuretic hormone (ADH), glucagon (peptide hormones) • insulin (protein) e1 M D C U Components of Endocrine System nd oc rin • Secreting cell • Hormone – chemical messenger secreted into bloodstream, stimulates response in another tissue or organ • Target cells : have receptors for hormone Endocrine system includes hormone producing cells in organs e.g. brain, heart and GI nd oc rin e1 M D C U Types of Endocrine Signaling U C M D nd oc rin e1 Part II : Hypothalamus & Pituitary gland nd oc rin e1 Thalamus M D C U Anatomy of Hypothalamus Tuber cinereum oc Infundibular stalk rin Median eminence e1 M D C U Anatomy of Hypothalamus: Boundaries nd Medial boundary = 3rd ventricle Lateral boundary - indistinct nd oc rin e1 M D C U Hypothalamic Nuclei Nucleus = groups of neurons in hypothalamus nd oc rin e1 M D C U Hypothalamus : Functions U The Hypothalamus: Hormones nd oc rin e1 M D C • Hormones – control secretion of hormones in the anterior pituitary – Releasing hormones (factors) – Inhibitory hormones (factors) nd oc rin e1 M D C U ADH and Oxytocin M D C U Hypothalamus and Pituitary Gland Main source of releasing/inhibitory factors nd ACTH TSH FSH, LH GH prolactin oc rin e1 ADH/oxytocin Releasing factors: CRH, TRH, GnRH, GHRH Inhibiting factors: somatostatin, dopamine ADH/oxytocin U Pituitary Gland nd oc rin e1 M D C (Hypophysis, Master gl., Neuroendocrine gl.) C U Pituitary: Gross Anatomy • 0.5 – 1 g in weight • In sella turcica (bony cavity at the base of the brain) M D • 1 cm in diameter nd oc rin e1 • Connected to the hypothalamus via pituitary stalk (infundibulum) U C M D Mamillary body Optic chiasma e1 Pituitary stalk nd oc rin Pituitary gland in sella turcica Sphenoidal air sinus U Embryonic Development of Pituitary nd oc rin e1 M D C Adenohypophysis : Neuroectoderm Neurohypophysis : Oral epithelium Adenohypophysis Pituitary Subdivision rin Terminology based on embryonic origin e1 M D C U Pituitary Subdivisions Pars distalis Clinical Terminology Anterior lobe nd oc Pars tuberalis Neurohypophysis Pars intermedia Pars nervosa Infundibulum Posterior lobe U Adenohypophysis M D C Pars tuberalis e1 Pars distalis nd oc rin Pars intermediate General Cell Types Diameter of secretory granules (nm) Somatotrope hGH Acidophilic 300-400 Mammotrope Prolactin Acidophilic 200 ACTH Basophilic 400-550 TSH Basophilic 120-200 FSH, LH Basophilic 250-400 rin nd Thyrotrope oc Corticotrope Gonadotrope M D Hormones e1 Specific Cell Types C U Cells in pars distalis Histology: Pars Distalis rin e1 M D C U very cellular, arranged in clumps and cords between sinusoids Chromophils nd Somatotropes (GH) Mammotropes (Prl) Basophils (blue/black) oc Acidophils (red/pink) Chromophobes (orange/gray) Thyrotropes (TSH) smallest cell type Corticotropes (ACTH) few granules Gonadotropes (FSH, LH) unstained cytoplasm D e1 rin oc nd C U C M D T A B I N ACTH immunoperoxidase stain nd oc rin Prolactin immunoperoxidase stain e1 M D C U Pituitary immunohistology Human growth hormone (HGH) immunoperoxidase stain C Extension of the hypothalamus M D – pars nervosa – pituitary stalk oc rin e1 – median emminence Axons from supraoptic nuclei – vasopressin (ADH) Axons from paraventricular nuclei – oxytocin nd • U Neurohypophysis rin e1 M D C U Neurohypophysis histology nd oc • Axons : unmyelinated • Pituicytes : as glia cell • Fenestrated capillaries : from inferior hypophyseal a. Nerve fibers in relation to capillaries and pituicytes nd oc rin e1 M D C U Neurohypophysis : H&E Histology Axon oc rin e1 M D C - Herring bodies – neurosecretory granules accumulated close proximity to axon terminal nd • U Herring body (Immunohistochemical staining of ADH) e1 rin oc nd U C M D Herring body nd oc rin e1 M D C U Pituitary Hormones & Effects nd oc rin e1 M D C U Growth Hormone (hGH) nd oc rin e1 M D C U Prolactin (PRL) nd oc rin e1 M D C U Gonadotropins (LH, FSH) nd oc rin e1 M D C U Thyroid stimulating hormone nd oc rin e1 M D C U Adrenocorticotropic Hormone nd oc rin e1 M D C U Hypothalamic-hypophysial vessels U Fenestrated capillaries in pituitary gland Transmission electron microscope M D C Scanning electron microscope Capillary nd oc rin H E P e1 P E: Endothelial cells H: Hormone producing cells P: Pericytes F: Fenestration E F F C U PITUITARY ADENOMA M D Hypophysectomy nd oc rin e1 Transsphenoidal Approach U C M D nd oc rin e1 PART III : Pineal gland oc rin e1 M D C Cone-shaped, 5-8 mm. in length Connected to roof of 3rd ventricle by a stalk No direct nerve connection with brain Function is regulated by numerous postganglionic sympathetic nerves from the superior cervical ganglion nd – – – – U Pineal Gland : Anatomy nd oc rin e1 M D C U Embryonic Development of Pineal gland nd oc rin e1 C M D - Capsule = Pia mater - Cells Parenchyma •Pinealocyte –Round shape, slightly stained cytoplasm –Nuclei relatively large with prominent nucleoli –2 or more processess with bulb ending (not demonstrated with H&E) –organized into cords/clusters •Glial-like interstitial cell –surround and mingle with the pinealocytes making up peculiar aggregates - Stroma •CNT, fenestrated vessels, nerves •Corpora arenacea U Pineal Histology U Brain Sand (Corpora Arenacea) M D C • Adult pineal contain lamellated, calcified, basophilic glycoprotein nd oc rin e1 Radiologic marker nd oc rin e1 M D C U Pineal gland: Histology nd oc rin e1 M D C U Pineal Histology : EM e1 M D C U Pineal Gland : Melatonin nd oc rin • Peak secretion 1-5 yr. olds, by puberty 75% lower • Produces serotonin by day, converts it to melatonin at night • May regulate timing of puberty/ circadian rhythms (biological clock) • During sleep, plasma levels of melatonin increase & then decrease before awakening • Clinical Use : insomnia, jet lag U C M D nd oc rin e1 PART IV : Thyroid e1 • Inferior to larynx, anterior and lateral sides of trachea M D C U Thyroid Gland : Gross Anatomy nd oc rin • Functions - Produces - thyroid hormone - calcitonin M D C U Thyroid Gland : Gross Anatomy • Consists of e1 1. Lateral lobes 3. Pyramidal lobe rin 2. Isthmus nd oc (remnant of development) C U Thyroid Gland : Gross Anatomy • Venous Drainage rin e1 - Superior thyroid artery - Inferior thyroid artery - Thyroidea ima artery (10%) branch from brachiocephalic trunk M D • Arterial Supply oc - Superior and middle thyroid v. nd to internal jugular v. - Inferior thyroid v. to brachiocephalic v. nd oc rin C M D e1 • Normal size : 15-30 gram • Abnormal size (reported by weight) 1. Diffused enlargement 2. Thyroid nodule U Thyroid Gland : Gross Anatomy M D • Moved with swallowing C U Thyroid Gland : Gross Anatomy nd oc rin e1 – by anterior and posterior suspensory ligament of thyroid gland (posterior = ligament of Berry) oc Fibrous CNT Loose CNT, Fenestrated capillary Thyroid follicles, Parafollicular cells Follicular cells nd Capsule: Stroma: Parenchyma: Follicles : rin e1 M D C U Thyroid : H&E Histology Colloids : Thyroglobulin C U Thyroid Gland : Parenchyma M D Follicular Cells • Acini form • Lumen with colloid oc • C (Calcitonin ) cells rin Parafollicular Cells • Round shape/round nucleus • Pale cytoplasm nd e1 • Simple cuboidal epithelium • Small cytoplasmic granule nd oc rin e1 M D C U C cell : H&E, IHC and EM e1 M D C U Thyroid Functions • Thyroid follicles nd oc rin – filled with colloid and lined with simple cuboidal epith. (follicular cells) that secretes 2 hormones, T3+T4 – Thyroid hormone • body’s metabolic rate and O2 consumption • calorigenic effect - heat production • heart rate and contraction strength • respiratory rate • stimulates appetite and breakdown CHO, lipids & proteins C U Calcitonin Functions M D • C (calcitonin or parafollicular) cells nd oc rin e1 – produce calcitonin that blood Ca+2, promotes Ca+2 deposition and bone formation especially in children nd oc rin e1 M D C U Thyroid : Hormone Synthesis • More potent rin • Mostly bind with TBG e1 • Less potent • Short halflife (18 hr) • Produced 20-30 µg/d nd oc – Peripheral conversion from T4 – Follicular cell T4 = Thyroxine M D T3 = Triiodothyronine C U Thyroid Hormones • Long halflife (5-7 days) • Mostly bind with TBG • Produced 80-100 µg/d – Follicular cell nd oc rin e1 M D C U Hashimoto's Thyroiditis nd oc rin e1 M D C U Thyroid : Follicular Adenoma oc rin e1 M D C U Thyroid : Grave’s Disease nd exophthalmos pretibial myxedema nd oc rin e1 M D C U Thyroid : Grave’s Disease nd oc rin e1 M D C U Thyroid : Grave’s Disease C U Thyroid : Medullary carcinoma nd oc rin e1 M D “C” Cells Cancer Related with Multiple Endocrine Neoplasia (MEN) C U Thyroid : Medullary carcinoma nd oc rin e1 M D “C” Cells Cancer Related with Multiple Endocrine Neoplasia (MEN) U C M D nd oc rin e1 PART V : Parathyroid nd oc rin e1 C M D • 10% of individual have 2-3 glands • Each weighs 35-40 g • Landmark : Fatty Mass U Parathyroid Glands Anatomy nd oc rin e1 M D C U Parathyroid Histology : H&E nd oc rin e1 M D C U Parathyroid Histology : H&E nd oc rin e1 M D C U Parathyroid Histology : H&E nd oc rin e1 M D C U Parathyroid Histology : H&E U Parathyroid Gland : Parenchyma M D • Smaller, rather basophilic • Larger cells, eosinophilic nd • Unknown function oc • Arranged in small cluster rin Oxyphil Cells e1 • Predominate and contain cytoplasmic granule • Synthesize parathyroid hormone (PTH) C Chief (Principal) Cells Parathyroid Gland : Stroma • Fat, increase with age up to 25 years, occupied 30% of adult gland nd oc rin e1 M D C U Parathyriod Hormone: Functions nd oc rin e1 M D C U Parathyriod v.s. Calcitonin • Overactive neuron, resulting in Tetany • Too low Calcium nd oc rin e1 Hypo PTH • Moderate : impaired muscle/kidney M D Hyper PTH • Severe : Bone destruction C U Parathyroid Homeostatic Imbalances U C M D nd oc rin e1 PART VI : Adrenal Glands nd oc rin e1 M D C U ADRENAL (SUPRARENAL) GLANDS C U Adrenal Gland Anatomy M D • Cortex – Corticosteroid – glandular e1 • Medulla rin – Catecholamines – neurohormonal nd oc • Epinephrine • Norepinephrine C U Cortical Adrenal Zones (L. Glomus=ball) thin outermost zone 15% of cortical vol. • zona fasiculata (L. Fascis=bundle) thick middle zone 80% of cortical vol. (L. rete=net) thin inner zone 5-7% of cortical vol. rin e1 M D • zona glomerulosa nd oc • zona reticularis nd oc rin e1 M D C U Cortical Adrenal Histology: Low magnification nd oc rin e1 M D C U Adrenal Gland Histology reticularis U fasciculata capsule nd oc rin e1 M D C medulla glomerulosa oc rin e1 M D C U Zona glomerulosa Renin-angiotensin system (RAS) Aldosterone Na+ resorption nd • columnar in shape and are arranged in irregular cords • cells adjacent to the capsule are arranged in regular "arcades". • cells have less cytoplasm than the Zona Fasciculata, so appears as a darker layer (at lower powers) • boundaries between zones are indistinct. nd oc rin e1 M D C U Adrenal gland and RAAS system nd oc rin e1 M D C • Polyhedral in shape • Light appearance (abundant lipid droplets) • Arranged in long straight columns U Zona fasiculata CRF ACTH glucocorticoids Sex steroids Metabolic control U Zona reticularis M D C • Cells are noticeably smaller & darker than ZF cells • Arranged in an irregular network of branching cords and clumps • Anastomose with one another, some cells contain lipofuscin e1 CRF oc Androgens (esp.DHEA) rin ACTH nd glucocorticoids C U Cortical Adrenal Cells : EM M D • Features of steroid-secreting cells nd oc rin e1 – Abundant smooth endoplasmic reticulum – Mitochondria with tubular cristae in the zona fasciculata and zona reticularis, shelf-like cristae in the zona glomerulosa – Numerous lipid droplets – Secretion is by diffusion, with no hormone storage U Adrenal Medulla M D • columnar in shape and rather basophilic • pale-staining granular cytoplasm • arranged in clusters, C Chromaffin cell • mixed with sinusoidal capillaries /preganglionic sympathetic fiber Ganglion cells nd oc rin e1 • round or polygonal with prominent nuclei • arranged in clusters U Medullary Hormones nd oc rin e1 M D C • Innervated by preganglionic sympathetic fibers – consists of modified neurons called chromaffin cells – stimulation causes release of (nor-epinephrine) C U Adrenal Medulla : EM M D TEM (magnification = 8400x) Epinephrine-Secreting cells (ESC) - 75%approximately nd oc rin e1 - small homogenous granule Norepinephrine-Secreting cells (NSC) - 25% approximately - dense-core, larger granules nd oc rin e1 M D C U Hormone related to adrenal gland nd oc rin e1 M D – Superior adrenal a. – Middle adrenal a. – Inferior adrenal a. C • via the 3 suprarenal arteries U Vasculature of the adrenal gland e1 M D 0) Capsular capillaries 1) Cortical sinusoidal capillaries 2) Medullary capillaries C • Intra-adrenal arterial subdivisions U Vasculature of the adrenal gland (2) oc rin 1 nd 2 C M D Addison’s U Adrenal Cortex Disorder nd oc rin e1 Normal ACTH hypersecretion rin • Hyposecretion leads to Addison’s Disease oc – Deficits in glucocorticoids and mineralcorticoids nd C e1 – ACTH-releasing tumors or side effects of corticoid drugs. M D • Hypersecretion leads to Cushing’s disease U Adrenal Cortex Imbalances oc rin e1 M D C U Adrenal medulla tumor : Pheochromocytoma • Tumor arising most commonly from the adrenal gland nd • Cause headaches, sweating, rapid rise and fall in blood pressure, fast heartbeat , etc. • From making excessive adrenaline (catecholamine) U C M D nd oc rin e1 PART VII : Other endocrine organs C Exocrine 98% produces digestive enzymes Endocrine pancreas (Islets of Langerhans) (1-2%) oc rin e1 M D • cells: glucagon (15-20%) • cells: insulin (60-80%) • cells: somatostatin (less than 5%) •F cells: pancreatic polypeptide (PP) •Etc: motilin, serotonin, substance P, Vasoactive intestinal peptide (VIP) nd • • U Pancreas e1 rin oc nd U C M D Thymus M D C U Gonads nd Ovary oc rin e1 Testis e1 * nd oc rin * * M D C U Other Hormones Organs Hormones Heart Atrial Natriuretic Peptide (ANP) Skin Cholecalciferol Adipose Tissue Leptin Kidney Erythopoietin Gastrointestinal Digestive hormones Liver Albumin Liver hormones