Endocrine - Embryology and Anatomy

Question 1

Thyroid development

• Thyroid diverticulum
  
  • Arises from…
  • Connected to…
• Foramen cecum
• Most common ectopic thyroid tissue site
• Thyroglossal duct cyst

Answer 1

• Thyroid diverticulum
  
  • Arises from floor of primitive pharynx, and descends into neck.
  • Connected to tongue by thyroglossal duct, which normally disappears but may persist as pyramidal lobe of thyroid.
• Foramen cecum is normal remnant of thyroglossal duct.
• Most common ectopic thyroid tissue site is the tongue.
• Thyroglossal duct cyst [A] presents as an anterior midline neck mass that moves with swallowing or protrusion of the tongue
  
  • vs. persistent cervical sinus leading to branchial cleft cyst in lateral neck

Question 2

Adrenal cortex and medulla

• Derivations
  
  • Adrenal cortex
  • Medulla
• Pheochromocytoma
• Neuroblastoma

Answer 2

• Derivations
  
  • Adrenal cortex is derived from mesoderm
  • Medulla is derived from neural crest
• Pheochromocytoma
  
  • Most common tumor of the adrenal medulla in adults.
  • Episodic hypertension.
• Neuroblastoma
  
  • Most common tumor of the adrenal medulla in children.
  • Rarely causes hypertension.

Question 3

Adrenal cortex and medulla

• For each
  
  • Location (cortex vs. medulla)
  • Primary regulation control
  • Secretory products
• Zona Glomerulosa
• Zona Fasiculata
• Zona Reticularis
• Chromaffin cells

Answer 3

• Zona Glomerulosa
  
  • Location: Cortex
  • Primary regulation control: Renin-Angiotensin
  • Secretory products: Aldosterone
• Zona Fasiculata
  
  • Location: Cortex
  • Primary regulation control: ACTH, CRH
  • Secretory products: Cortisol, sex hormones
• Zona Reticularis
  
  • Location: Cortex
  • Primary regulation control: ACTH, CRH
  • Secretory products: Sex hormones (e.g. androgens)
• GFR corresponds with Salt (Na+), Sugar (glucocorticoids), and Sex (androgens).
  
  • “The deeper you go, the sweeter it gets.”
• Chromaffin cells
  
  • Location: Medulla
  • Primary regulation control: Preganglionic sympathetic fibers
  • Secretory products: Catecholamines (epinephrine, norepinephrine)

Question 4

Adrenal gland drainage

• Left
• Right
• Same as…

Answer 4

• Left adrenal gland –>Ž left adrenal vein –>Ž left renal vein –>Ž IVC.
• Right adrenal gland –>Ž right adrenal vein –>Ž IVC.
• Same as left and right gonadal vein.

Question 5

Posterior pituitary gland

• AKA…
• Secretes…
• Derived from…

Answer 5

• AKA neurohypophysis
• Secretes vasopressin (antidiuretic hormone, or ADH) and oxytocin
  
  • Made in the hypothalamus and shipped to posterior pituitary via neurophysins (carrier proteins).
• Derived from neuroectoderm.

Question 6

Anterior pituitary gland

• AKA…
• Secretes…
• Derived from…
• Subunits
  
  • α
  • β
• Cell productions
  
  • Acidophils
  • Basophils

Answer 6

• AKA adenohypophysis
• Secretes FSH, LH, ACTH, TSH, prolactin, GH, melanotropin (MSH).
  
  • FLAT PiG: FSH, LH, ACTH, TSH, Prolactin, GH.
• Derived from oral ectoderm (Rathke pouch).
• Subunits
  
  • α subunit—hormone subunit common to TSH, LH, FSH, and hCG.
  • β subunit—determines hormone specificity.
• Cell productions
  
  • Acidophils—GH, prolactin.
  • Basophils—FSH, LH, ACTH, TSH.
    
    • B-FLAT

Question 7

Endocrine pancreas cell types

• Islets of Langerhans
  
  • Definition
  • Derivation
• α
• β
• δ

Answer 7

• Islets of Langerhans
  
  • Collections of α, β, and δ endocrine cells.
  • Islets arise from pancreatic buds.
• α = glucagon (peripheral)
• β = insulin (central)
  
  • Insulin (β cells) inside.
• δ = somatostatin (interspersed).