Pituitary Histology Flashcards by Babe Lincoln

The Anterior pituitary is embryonically derived form the

oropharynx ectoderm

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The Posterior Pituitary is embryonicall derived from the

neuroectoderm

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The Adenohypophysis is comprised of what 3 components?

Pars tuberalis
Pars distalis
Pars intermedia

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The Neurohypophysis is comprised of what 2 components?

Pars nervosa – infundibular process
(neural lobe)
Infundibulum
(neural stalk)

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The pituitary blood supply is from what system?

Hypothalamohypophyseal Portal System

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The pituitary blood supply comes from what 2 sets of vessels?

Superior hypophyseal arteries

and Inferior hypophyseal arteries

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These arteries arise from internal carotid arteries & posterior communicating artery of circle of Willis. They
Supply pars tuberalis, median eminence & infundibulum

Superior hypophyseal arteries

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These arteries arise from internal carotid arteries and

Supply pars nervosa

Inferior hypophyseal arteries

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Most of ______ lobe has no direct arterial supply

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describe the portal blood supply

Arteries give rise to fenestrated capillaries (primary capillary plexus) that

drain into portal veins that

drain into hypophyseal portal veins that

give rise to a second fenestrated sinusoidal capillary network (secondary capillary plexus)

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Neuroendocrine secretions of hypothalamus nerves are carried through median eminence and infundibulum into the ____________

pars distalis

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which (anterior or posterior) is darkly and lightly stained

Anterior = dark
Posterior = light (nerves don't stain well)

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which lobe makes hormones, so cells are filled with rER and ribosomes that stain dark with H&E stains?

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which lobe is primarily nonmyelinated axons, nerve endings and blood vessels that stain faintly with H&E stains?

Posterior

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what is the pars nervosa?

neurohypophysis (posterior pituitary)

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what is the pars distalis?

adenohypophysis (anterior pituitary) 
75% of anterior pituitary
Parenchyma
Anastomosing cords of cells
Sinusoidal capillaries
Colloid (cysts)
Cell types: chromophobes &amp; chromophils

Where are chromophobes & chromophils found?

Pars distalis

Chromophobes are what type of cells?

Degranulated chromophils

Faintly stained

Chromophils are what type of cells?

Acidophils (~40%) - Pink stained

Basophils (~10%) - Purple stained

Acidophil somatotropes secrete what?

Growth hormone (GH) or somatotropin (STH)
Acidophilic secretory vesicles

Acidophil Mammotropes (Lactotropes) secrete what?

Prolactin (PRL)
Acidophilic secretory vesicles
Increase during pregnancy & lactation

Basophil Thyrotropes secrete what?

Thyroid stimulating hormone (TSH)

Basophilic secretory vesicles

Basophil Gonadotropes secrete what?

The largest cells in the adenohypophysis
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH) in female or Interstitial stimulating hormone (ICSH) in male
Secretory vesicles contain both FSH & ICSH

Basophil cotricotropes secrete what?

Adrenocorticotropic hormone (ACTH)
Melanocyte-stimulating hormone (MSH)

Pars intermedia is what? what does it secrete?

function unclear Basophilic cells & chromophobes Produce melanocyte-stimulating hormone (MSH), corticotropes Rathke’s cysts = remnants of Rathke’s pouch = colloid Follicles lined by cuboidal epithelium and filled with colloid

What highly vascularized area has... Superior hypophyseal arteries terminate here to form primary plexus of portal system Basophilic cells arranged in cords alongside blood vessels Cells contain FSH and LH

Pars tuberalis

What Consists largely of secretory nerve cells (100,000 unmyelinated axons Cell bodies lie in supraoptic and paraventricular nuclei of hypothalamus)

Pars nervosa

What tract Passes through infundibular stalk, Ends in pars nervosa, and Terminate in rich capillary (fenestrated) plexus

Hypothalamic-hypophyseal tract

What storage vesicles synthesized in cell bodies Contain oxytocin or vasopressin/ADH (in different neurons), ATP, and neurophysins (specific binding proteins for oxytocin and vasopressin/ADH)

Neurosecretory vesicles of the pars nervosa

What are the “supportive” cells found throughout posterior lobe (Specialized neuroglial cells , Nuclei stain dark purple with an H&E stain)

Pituicytes

What are the functions of Oxytocin?

Small polypeptide (9 amino acids) Secretion induced by suckling (milk-ejection reflex) Causes contraction of myoepithelial cells surrounding alveoli and alveolar ducts of mammary glands Stimulates uterine smooth muscle contraction

What are the functions of Vasopressin (anti-diuretic hormone, ADH)?

Small polypeptide Increases permeability of distal convoluted and collecting tubules to water in the kidney (Increases water resorption and concentrates urine)

ADH secretions stimulated by:

Increase in plasma osmolality | Decrease in blood volume

This disorder is characterized by a Lack of ADH or mutation of receptor Victims may excrete 20 liters of urine/day (polyuria) and drink enormous quantities of water

Diabetes insipidus