Term
Adenohypophysis
consists of?
embryology |
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Definition
Part of the pituitary gland
consists of: pars tuberalis, pars distalis (anterior lobe), pars intermedia (diffuse region)
forms from evagination of the oral ectoderm
moves upward to meet the post pit
termed "Rathke's pouch" |
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Term
Neurohypophysis
consists of?
embryology
where do its axons originate?
25% of pars nervosa is composed of __
Herring bodies |
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Definition
Part of the pituitary gland
consists of: median eminence, infundibular stem, pars nervosa (posterior lobe)
forms as an extension of the hypothalamus
- composed of neural tissue, is a functional part of the hypothalamus
Its 100,000 unmyelinated axons of secretory neurons originate in the SON & PVN of the hypothalamus
25% of pars nervosa is composed of pituicytes
- highly branched glial (support) cells
Herring bodies - accumulation of granules visible with light microscopy |
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Term
| Blood supply to the pituitary |
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Definition
Blood supply to pars distalis = hypothalamohypophyseal portal circulation
blood from adeno- & neurohypophysis drains into sinuses
the sup & inf hypophyseal arteries supply pars nervosa, small supply to stalk
- capillary network in pituitary stalk forms the short hypophyseal vessels
- also delivers blood into sinusoids of the pars distalis
Sup hypophyseal a -> capillary bed -> portal vv -> capillary bed (pars distalis) -> hypophyseal v |
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Term
Pars distalis
Cells types (2) and what they consist of |
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Definition
Cords of cell interspersed with capillaries
Accounts for 75% of pituitary mass
Chromophobes (no H&E, may be support cells, may have been recently secreted)
Chromophils (store & make hormones, stains, basophils/acidophils, named for the hormone they secrete, specific hormone produced can be identified with histo procedures) |
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Term
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Definition
Rudimentary region in the pituitary
Made up of cords, follicles whose function is unknown
space b/t adeno- and neurohyphysis |
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Term
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Definition
outer covering of pituitary stalk
most cells secrete gonadotropins (LH, FSH)
arranged as cords alongside blood vessels |
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Term
Axons of the neurohypophysis
ADH & oxytocin
where is the terminal axon? |
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Definition
Neurosecretory granules concentrate at the dilated, terminal portions of the axon
- ADH and oxytocin are produced at the hypothalamus, move down to post pit, stored & released when triggered
- neurosecretory material is composed of either: oxytocin, ADH, neurophysin (binding pr, specific for each hormone)
terminal axon is apposed to fenestrated capillaries in the pars nervosa |
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Term
tumors of the hypophysis
about ___ produce enough hormone to produce clinical symptoms
what cells do tumors usually come from?
how might tumors present? |
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Definition
usually benign
about 2/3 produce enough hormone to produce clinical symptoms
tumors commonly from GH, prolactin, or ACTH producing cells of pars distalis
may present as vision problems b/c it's pressing down on optic chiasm |
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Term
Thyroid gland
derived from?
location?
major hormone products?
epithelial lining?
where are TSH receptors located |
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Definition
consists of two lobes united by an isthmus, composed of follicles
sphere lined by a simple epithelium, lumen contains colloid
derived from cephalic portion of the alimentary canal endoderm
located in cervical region anterior to larynx
T3, T4, TSH (TSH = main regulator of thyroid follicle)
epithelial lining ranges from simple squamous to low simple columnar
TSHR located on basal cell membrane of epithelial cell |
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Term
| Morphology of thyroid follicles |
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Definition
hypoactive - mostly simple squamous epithelium
hyperactive - TSH stimulation i/c height of epithelial cells, d/c quantity of colloid & size of follicle
thyroid epithelial cells can simultaneously synthesize, secrete, absorb, and digest proteins |
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Term
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Definition
a.k.a. C cells
part of the follicular epithelium or isolated clusters b/t thyroid follicles
contains numerous, small granules
contains calcitonin - lowers blood Ca++ via inhibition of bone resorption |
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Term
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Definition
enlarged, inflamed hypofunctioning thyroid (goiter)
mostly infiltrated with immune cells
blue cells - lymphocytic infiltrates
virtually no thyroid follicles |
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Term
| Primary diffuse hyperplasia |
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Definition
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Term
Parathyroid gland
embryo
histo
pathology |
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Definition
4 small glands located on posterior surface of the thyroid; one at each end of the upper & lower poles
derived from 3rd & 4th pharyngeal pouches
elongated, chord-like clusters of secretory cells
2 cell types: chief cells (make PTH), oxyphil cells (lot of mito, no known fn, i/c in # after puberty)
parathyroid adenoma - cells are too mitotically active |
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Term
Adrenal gland
cortex vs. medulla |
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Definition
cortex - coelomic intermediate mesoderm
medulla - neural crest cells
cortical cells don't store hormones as granules
hormones are synthesized & secreted on demand
cells have typical ultrastructure of a steroid producing cell - lot of sER, mitochondria |
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Term
Adrenal cortex
3 concentric layers |
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Definition
zona glomerulosa (15%) - immediately beneath connective tissue capsule, cells arranged as closely packed rounded clusters, surrounded by capillaries, secrete mineralcorticoids (aldosterone)
zona fasciculata (65%) - cells arranged as straight cords (1-2 cells thick), run perpendicular to surface, capillaries located b/t cords of cells, cells store lipid droplets & appear vacuolated, secrete glucocorticoids (cortisone, cortisol)
zona reticularis (7%) - innermost cortical layer, lies adjacent to medulla, cells arranged as irregular cords, secrete androgens & small amts of endrogens, lipofuscin & cell degradation may be seen |
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Term
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Definition
composed of polyhedral cells arranged in cords or clumps
profuse capillary supply w/ a few PS ganglion cells
cells are modified sympathetic, postganglionic neurons (derived from neural crest cells)
cells have lost axons & dendrites to become secretory cells
cells contain abundant membrane-bound electron dense secretory granules (storage form of epi/NE, contain ATP, binding protein chromogranin, enkephalin)
cells innervated by cholinergic endings of preganglionic sympathetic neurons |
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Term
Blood supply to adrenal gland
3 main arteries
vessels form a subcapsular plexus from which arise 3 groups of vessels
medulla vascularization |
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Definition
Superior suprarenal artery – from inferior phrenic artery
Middle suprarenal artery – from the aorta
Inferior suprarenal artery – from the renal artery
Arteries of the capsule
Arteries of the cortex that drains into the medulla
Arteries of the medulla that pass through the cortex (without feeding it) and form medullary capillaries
Consists of an arterial supply (medullary arteries) and a venous supply (cortical arteries)
• Medullary capillaries and cortical capillaries form the medullary veins
• These join to constitute the adrenal/suprarenal vein |
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Term
Islets of Langerhans
Histology
A, B, D, F cells |
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Definition
Represents the endocrine pancreas
Multihormonal endocrine structures
• Rounded clusters of cells within exocrine pancreas
• 1.0 million per pancreas
• Each islet is 100-200mm in diameter and contains several hundred cells
Consists of lightly stained, polygonal or rounded cells
Separated by a network of fenestrated capillaries
Both cells and vessels are innervated by autonomic nerve fibers
At least 4 cell types have been located in the islet
A Cells – regular granules with a dense core surrounded by a clear region
• Secretes glucagon
B Cells – irregular granules with a core formed by irregular crystals
• Secretes insulin
D Cells – secretes somatostatin – inhibits other cells
F Cells – secretes pancreatic polypeptide |
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Term
Pineal gland
size?
location?
histo
pinealocytes
astrocytes |
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Definition
a.k.a. epiphysis cerebri
Flattened organ about 5-8 mm in length and 3-5 mm in width
Located in the posterior extremity of the 3rd ventricle
Above the roof of the diencephalon, connected by a short stalk
Covered by the pia mater
Histology:
o Composed of cellular chords that form irregular lobules
o Cell types include pinealocytes and astrocytes
Pinealocytes
- Long and tortuous branches
- End as flattened dilations near vascular elements
- Cells produce melatonin
Astrocytes (Glial cells)
- Located between pinealocytes
- Contain large number of intermediate filaments
- Corpora arenacea – “brain sand” – increase from puberty |
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Term
| Innervation of the pineal gland |
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Definition
Unmyelinated axons end among pinealocytes
Synapses observed
Vesicles containing norepinephrine and serotonin are observed |
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