Pituitary Histology

Question 1

The Anterior pituitary is embryonically derived form the

Answer 1

oropharynx ectoderm

Question 2

The Posterior Pituitary is embryonicall derived from the

Answer 2

neuroectoderm

Question 3

The Adenohypophysis is comprised of what 3 components?

Answer 3

Pars tuberalis
Pars distalis
Pars intermedia

Question 4

The Neurohypophysis is comprised of what 2 components?

Answer 4

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

Question 5

The pituitary blood supply is from what system?

Answer 5

Hypothalamohypophyseal Portal System

Question 6

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

Answer 6

Superior hypophyseal arteries

and Inferior hypophyseal arteries

Question 7

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

Answer 7

Superior hypophyseal arteries

Question 8

These arteries arise from internal carotid arteries and

Supply pars nervosa

Answer 8

Inferior hypophyseal arteries

Question 9

Most of ______ lobe has no direct arterial supply

Answer 9

anterior

Question 10

describe the portal blood supply

Answer 10

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)

Question 11

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

Answer 11

pars distalis

Question 12

which (anterior or posterior) is darkly and lightly stained

Answer 12

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

Question 13

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

Answer 13

anterior

Question 14

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

Answer 14

Posterior

Question 15

what is the pars nervosa?

Answer 15

neurohypophysis (posterior pituitary)

Question 16

what is the pars distalis?

Answer 16

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

Question 17

Where are chromophobes & chromophils found?

Answer 17

Pars distalis

Question 18

Chromophobes are what type of cells?

Answer 18

Degranulated chromophils

Faintly stained

Question 19

Chromophils are what type of cells?

Answer 19

Acidophils (~40%) - Pink stained

Basophils (~10%) - Purple stained

Question 20

Acidophil somatotropes secrete what?

Answer 20

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

Question 21

Acidophil Mammotropes (Lactotropes) secrete what?

Answer 21

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

Question 22

Basophil Thyrotropes secrete what?

Answer 22

Thyroid stimulating hormone (TSH)

Basophilic secretory vesicles

Question 23

Basophil Gonadotropes secrete what?

Answer 23

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

Question 24

Basophil cotricotropes secrete what?

Answer 24

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

Question 25

Pars intermedia is what? what does it secrete?

Answer 25

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

Question 26

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

Answer 26

Pars tuberalis

Question 27

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

Answer 27

Pars nervosa

Question 28

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

Answer 28

Hypothalamic-hypophyseal tract

Question 29

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)

Answer 29

Neurosecretory vesicles of the pars nervosa

Question 30

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

Answer 30

Pituicytes

Question 31

What are the functions of Oxytocin?

Answer 31

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

Question 32

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

Answer 32

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

Question 33

ADH secretions stimulated by:

Answer 33

Increase in plasma osmolality

Decrease in blood volume

Question 34

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

Answer 34

Diabetes insipidus