EXAM #1: PITUITARY ANATOMY & HISTOLOGY Flashcards
What structures lie superior to the pituitary gland?
Diaphragma sellae* and hypothalamus
Dura mater that forms a roof over the pituitary–this is what the infandibulum passes through
What structures lie lateral to the pituitary gland?
Cavernous sinuses
What is contained within the cavernous sinuses?
Internal carotid arteries and cranial nerves
What structure lies anteroinferior to the pituitary gland?
Sphenoid sinus
*Note that this allows the pituitary gland to be accessed surgically via a “transsphenoidal approach” i.e. through the nose
What separates the pituitary gland from the sphenoid sinus?
Sella turcica
This is a depression in the sphenoid bone, containing the pituitary gland.
What major structures will be compromised by a pituitary tumor?
1) Internal carotid a. which can lead to infarction
2) CN III, V, VI i.e. CN palsy
What type of infarct results from stenosis of the internal carotid arteries secondary to a pituitary tumor?
“Watershed” infarct
What is empty sella syndrome?
This is a defect in the dura forming the digphragma sella
*Increased space allows for increased pressure to be placed on the pituitary gland from surrounding CSF
What are the three portions of the anterior pituitary gland? What is the major division?
1) Pars distalis (major)
2) Pars tuberalis (surrounds infandibulum)
3) Pars intermedia (between the first two)
What are the two major divisions of the posterior pituitary gland?
1) Pars nervosa (neurons)
2) Infundibular stalk
What is the embryonic origin of the anterior pituitary?
Oral ectoderm that develops into “Rathke’s Pouch” (and then the anterior pituitary)
What is the embryonic origin of the posterior pituitary?
Neuroectoderm
What are the two major signaling molecules that drive the development of the pituitary gland?
1) Bone morphogenic protein 4
2) Fibroblast growth factor 8
What is a pediatric craniopharyngioma?
This is when remnants of Ratheke’s pouch/cleft that do not regress in the formation of the anterior pituitary
What is an adult craniopharyngioma?
Anterior pituitary tumor that forms from mature cells
What structures form from the superior hypophysial artery? What region of the pituitary does it exert influence over?
1) Primary capillary plexus
2) Portal veins
2) Secondary capillary plexus
*Anterior pituitary
What is carried in the primary/secondary capillary plexi?
Releasing and inhibitory hormones from hypothalamus
What forms from the inferior hypophysieal artery? What region of the pituitary is it associated with?
Capillary plexus of the posterior pituitary
*Associated with the posterior pituitary
What is the normal histological appearance of the pars distalis?
Abundant reticular connective tissue
What does “scant reticular connective tissue” indicate?
Pituitary adenoma
What are the three types of cells in the pars distalis based on staining characteristics?
Basophil= dark Acidophil= lighter Chromophobe= lightest
What type of technique can be used to identify the functional classification of cells in the pituitary gland?
Immunocytochemistry
What hormone is produced by somatotropes?
Growth Hormone
Note that these are acidophils, and the most frequent cell type
How does GH induce its action?
Insulin-like growth factor-1 (from hepatocytes)
What is the function of GH?
Induce growth of bones at the epiphyseal plates
What is secreted by mammotropes?
Prolactin
What type of cell is the mammotrope histologically?
Acidophils
What is secreted by the gonadotropes?
FSH and LH
What type of cell is the gonadotrope histologically?
Basophil
What is secreted by the thyrotropes?
TSH
What type of cell is the thyrotrope histologically?
Basophil
What is secreted by the corticotropes?
ACTH and β-lipotrophic hormone
What type of cell is the corticotrope histologically?
Basophil
What hormone is increased by the action of ACTH?
Cortisol
Histologically, what happens to corticotropes in response to excess glucocorticoids?
“Crooke’s hyaline change”
Where are the cell bodies of the neurohypophysis?
Supraoptic and paraventricular nuclei of the hypothalamus
What is secreted by the neurohypophysis?
ADH and oxytocin
What are the supporting cells in the neurohypophysis?
Pituicytes
What is a herring body?
Neurosecretory terminal end of the axons from the hypothalamus in the posterior pituitary
What is the MOA of vasopressin?
1) Increased permeability of the collecting tubule to water
2) Vasoconstriction
What are the functions of oxytocin?
1) Uterine contraction
2) Milk release
