Endocrine Glands

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Endocrine Glands

• Part Zwei

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Adrenal (Suprarenal) Glands

• Adrenal Glands complex functions and origins.
• Paired organs attached to cranial pole of kidney
  hilum present divided into cortex and medulla.
• Cortex derived from mesodermal epithelium
  Medulla from neural crest and presumptive
  autonomic ganglia.
• Organ parts exist as separate organs in lower
  vertebrates chromaffin body and supra-renals.

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Adrenals

• Capsule of DICT with trabeculae of in cortex,
  reticular CT throughout parenchyma.
• Cortex
• a) Zona glomerulosa - outer zone (15)
• b) Zona fasciculata - middle zone (65)
• c) Zona reticularis - inner zone (7)
• Collectively the cortical zones secrete 40
  steroid products.

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Zona fasciculata Steroid Secreting
Cells Abundant SER No Secretory Granules
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Adrenal Cortex

• Zona Glomerulosa - large oval groups of simple
  columnar epithelium with no lumen Basophilic.
• - Secretions mineralocorticoids (aldosterone
  and deoxycorticosterone)
• - control electrolyte and water balance.

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Adrenal Cortex

• Zona Fasciculata - thickest layer large cuboidal
  cells in long cords two cells wide, perpendicular
  to surface of gland.
• - Fat droplets in cytoplasm outer two-thirds of
  cells have more lipid spongiocytes due to
  spongy appearance when fat is removed
  (vacuolization).
• - Inner third of cells have little fat and are
  more basophilic.
• - Secretions are glucocorticoids (hydrocortisone
  and cortisone) engage in carbohydrate metabolism.

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Adrenal Cortex

• Zona Reticularis - cords anastomose cuboidal
  cells with few fat droplets cells near medulla
  have deeply basophilic staining cytoplasm.
• Secretions are weak androgens and sex hormone
  precursors e.g. dehydroepiandrosterone (DHEA),
  and androstenedione.

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ANP
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Adrenal

• Medulla - cells ovoid apolar neurons influenced
  by adjacent steroid secretions, and arranged in
  short, anastomosing cords.
• Cytoplasm has granules that stain brown with
  potassium dichromate (Chromaffin Reaction). Ergo,
  Chromaffin granules.

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Adrenal Medulla

• Staining granules are precursors to epinephrine
  (adrenalin). Autonomic ganglion cells are also
  present.
• Secretions are catecholamines epinephrine (80)
  and nor-epinephrine nor- epinephrine is a
  precursor (synthetic intermediate) to epinephrine.

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Thyroid

• Thyroid Gland - controls general body metabolism.
  Thyroxine T3 and T4.
• Complex capsule
• outer areolar layer
• inner DICT layer.
• Gland in two bodies, one on each side of the
  larynx connected by a narrow isthmus across the
  trachea.
• Only endocrine gland to store its secretion
  product in large quantities.
• Derived from gut endoderm

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Thyroid

• Parenchyma
• Follicles lined with low simple cuboidal
  epithelium.
• Follicles filled with colloid thyroglobulin is a
  large glycoprotein (660 kDa)
• TSH stimulates endocytosis, proteolysis in
  lysosome ? liberation of triiodotyrosine,
  tetraiodotyrosine.
• Membrane permeable, binds to TBG in plasma

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Thyroid

• Two types of parenchymal cells
• a) Follicular cells simple cuboidal
  epithelium.
• b) Parafollicular cells occur outside and
  between follicles (derived from neural crest). C
  cells, secrete calcitonin hypocalcemic,
  inhibits osteoclast activity. Parathyroid
  antagonist.

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Larger Cells, Stain Lighter Not part of
follicle Secrete Calcitonin
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Goiter

• Chronic stimulation of thyroid
• Gland by TSH
• Hypertrophy of follicular
• Epithelium
• Iodine deficiency
• Goitrogens

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Parathyroid

• Parathyroid Gland controls body calcium release.
  (hypercalcemic)
• Four small tissue bodies stroma inconspicuous of
  thin areolar CT may even be embedded in the
  thyroid.
• Parenchyma of simple cuboidal epithelial cells in
  cords with occasional follicles.

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Parathyroid

• Two Cell Types
• - Chief or Principal cells - small cells forming
  most of the gland. Secrete parathyroid hormone
  (PTH).
• Hypercalcemic, stimulates osteoclasts.
• Increases Ca2 reabsorption in renal tubules
• Increases Calcitriol by kidney (inc. gut Ca2
  abs.)
• - Oxyphil or Acidophil cells - large, acid cells
  in clumps after the tenth year. Function- unknown

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