Download Endocrine Organs - Histology on the Fly

Endocrine
Organs
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 and
paraventricular nuclei of hypothalamus
 Produce vasopressin (ADH) and oxytocin in
nuclei then travel to pars nervosa via axons
to the Herring bodies
o Herring bodies (i.e. axon terminals)
 ADH and Oxytocin released with neural
stimulation
o Pituitcytes - glial cells
 Infundibular stalk
•
Video recording
o Pituitary gland
•
Microscope images
o 4x
o 10x
Adrenal (Suprarenal) Gland
•
Function
o Adrenal cortex – mesoderm origin, secrete steroid hormones
o Adrenal medulla – neural crest origin; secrete epinephrine and
norepinephrine
•
Location
o Retroperitoneal organs located on the superior poles of the kidneys,
embedded in adipose tissue
•
Structure
o 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 recording
o Adrenal gland
•
Microscope images
o Adrenal cortex
 10x
 40x
o Adrenal medulla
 10x
 40x
Thyroid Gland
•
Function
o Secretion of hormones thyroxine (T3), tri-iodothyronine (T4) and
calcitonin
o Hormones are important for metabolism, growth and calcium regulation
•
Location
o Located in the cervical region anterior to the larynx
o Consists of two lobes united by an isthmus; may have an accessory
pyramidal lobe
•
Structure
o 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 calcitonin
o Decrease blood calcium
•
Video recording
o Thyroid and parathyroid glands
•
Microscope images
o Thyroid gland
 4x
 10x
 40x
Parathyroid Gland
•
Function
o Produces parathyroid hormone which is involved in calcium regulation
•
Location
o Fur to six oval glands located on the posterior surface of the thyroid gland
•
Structure
o 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 granules
o Secrete parathyroid hormone
 Increases blood calcium
 Oxyphil cells
• Smaller nucleus
• More cytoplasm; eosinophillic
• Function unknown
• Suggest they are transitional derivatives of chief cells
•
Video recording
o Thyroid and parathyroid glands
•
Microscope images
o 10x
o 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