Endocrine Organs - Histology on the Flyhistologyonthefly.com/pdfs/endocrine01.pdf · Structure . o...
Transcript of Endocrine Organs - Histology on the Flyhistologyonthefly.com/pdfs/endocrine01.pdf · Structure . o...
Pituitary Gland (Hypophysis)
• Function o Production of hormones
• Location
o Connected to the hypothalamus via an infundibulum situated within the sella turcica of the sphenoid bone
• Structure o Anterior pituitary gland (Adenohypophysis)
10x 40x Derived from the pharynx Pars distalis
• 75% of adenohypophysis • Thin fibrous capsule • Cords of epithelial cells interspersed with fenestrated
capillaries • Cells
o Chromophils Secretory cells with cytoplasmic granules Identified by affinity for dyes Acidophils
• Somatotrophs (m/c) o Growth hormone
• Mammotrophs o Prolactin
Basophils • Gonadotrophs
o Follicle stimulating hormone o Luteinizing hormone
• Corticotrophs o Adrenocorticotropic hormone
• Thyrotropic o Thyroid stimulating hormone
o Chromophobes Weakly stained Few secretory granules Stem cells
Pars tuberalis • Surrounds hypophyseal stalk (infundibulum) • Cuboidal to columnar cells • Well vascularized
Pars intermedia• 10x• 40x• Cuboidal cell-lined cysts
o Remnants of ectoderm• Basophils
o Pro-opiomelanocortin (prohormone) Forms melanocyte stimulating hormone
o Posterior pituitary gland (Neurohypophysis) Pars nervosa
• No secretory cells• Neural tissue
o Axons of neurons from supraoptic andparaventricular nuclei of hypothalamus Produce vasopressin (ADH) and oxytocin in
nuclei then travel to pars nervosa via axonsto the Herring bodies
o Herring bodies (i.e. axon terminals) ADH and Oxytocin released with neural
stimulationo Pituitcytes - glial cells
Infundibular stalk
• Video recordingo Pituitary gland
• Microscope imageso 4xo 10x
Adrenal (Suprarenal) Gland
• Functiono Adrenal cortex – mesoderm origin, secrete steroid hormoneso Adrenal medulla – neural crest origin; secrete epinephrine and
norepinephrine
• Locationo Retroperitoneal organs located on the superior poles of the kidneys,
embedded in adipose tissue
• Structureo Capsule
Dense connective tissue• Produces septa into the gland as trabeculae
o Bring in blood and lymph vessels and nerve fibers
o Adrenal Cortex Zona glomerulosa (15% of cortex)
• Just beneath the capsule• Similar looking to glomeruli of the kidney• Closely packed small columnar cells• Produce mineralcorticoids (i.e. aldosterone)
Zona fasciculata (65%-80% of cortex)• Large polyhedral cells• Longitudinal sinusoidal capillaries between cells• Secrete glucocorticoids (i.e. cortisol)
Zona reticularis (10% of cortex)• Smaller cells• Secrete dehydroepiandrosterone (DHEA)
o Precursor to testosterone
o Adrenal Medulla Chromaffin cells
• Large, pale-staining polyhedral cells• Modified sympathetic postganglionic neurons• Granulated
o Secrete epinephrine and norepinephrine
• Video recordingo Adrenal gland
Thyroid Gland
• Functiono Secretion of hormones thyroxine (T3), tri-iodothyronine (T4) and
calcitonino Hormones are important for metabolism, growth and calcium regulation
• Locationo Located in the cervical region anterior to the larynxo Consists of two lobes united by an isthmus; may have an accessory
pyramidal lobe
• Structureo Capsule
Dense connective tissue• Form septa
o Bring in blood and lymph vessels and nerve fibers
o Thyroid Follicles Surrounded by follicular cells (principle cells)
• Simple cuboidal to columnar epithelium• Basophilic cytoplasm• Secrete thyroglobulin
o Binds with Iodide in colloid to from T3 and T4 Lumen filled with colloid
• Gelatinous fluid filled with precursors to thyroid hormone
o Parafollicular Cells (Clear cells or C cells) Lie in clusters outside the thyroid follicles Contain secretory granules
• Secrete hormone calcitonino Decrease blood calcium
• Video recordingo Thyroid and parathyroid glands
• Microscope imageso Thyroid gland
4x 10x 40x
Parathyroid Gland
• Functiono Produces parathyroid hormone which is involved in calcium regulation
• Locationo Fur to six oval glands located on the posterior surface of the thyroid gland
• Structureo Capsule
Dense connective tissue• Form septa
o Bring in blood and lymph vessels and nerve fibers Adipose tissue increases with age
o Cells Chief cells
• Acidophilic cytoplasm with many granuleso Secrete parathyroid hormone
Increases blood calcium Oxyphil cells
• Smaller nucleus• More cytoplasm; eosinophillic• Function unknown• Suggest they are transitional derivatives of chief cells
• Video recordingo Thyroid and parathyroid glands
• Microscope imageso 10xo 40x
Pineal Gland
• Function o Secretion of melatonin, influenced by light and dark periods of the day
• Location
o Epithalamus of the brain (roof of diencephalon)
• Structure o Capsule
Pia Mater • Form septa
o Bring in blood and lymph vessels and nerve fibers o Cells
Pinealocytes • Basophilic cells with one or two long processes
o Secrete melatonin Interstitial cells
• Glial cells • Deeply stained elongated nuclei