Pituitary Histology

Question 1

differentiate between the nuerohypophysis and adenohypophysis

Answer 1

neurohypophysis/pars nervosa is the lightest staining, central region on a section of the pituitary with pituicytes and neurosecretory granules; the adenohypophysis surrounds the pars nervosa in various shades of stain

Question 2

differentiate between axons and neurosecretory bodies in the neurohypophysis

Answer 2

astrocytes have the large euchromatic nuclei and the neurosecretory bodies are filled with neurosecretory granules; both stand out against the background of primarily unmyelinated axons

Question 3

list the hormones stored in neurosecretory bodies in the neurohypophysis

Answer 3

oxytocin and ADH

Question 4

what type of glial cells are present in the neurohypophysis and what are they called?

Answer 4

pituicytes: a type of astrocyte/glial/support cell with large, euchromatic nuclei

Question 5

explain why there are axons, but no neuronal cell bodies in the neurohypophysis

Answer 5

the neuronal cell bodies (supraoptic and paraventricular) are located in the hypothalamus, and send their axons down to form the pars nervosa/neurohypophysis

Question 6

differentiate between the 3 subdivisions of the adenohypophysis

Answer 6

pars intermedia: stains more basophilically than the pars nervosa; contains colloid and melanotrophs

pars distalis: contains chromophils and chromophobes; chromophils include acidophils and basophils

pars tuberalis: densely packed basophilic cells with melatonin receptors

see the diagram in the powerpoint for all three together to differentiate!

Question 7

which hormone receptors do the cells of the pars tuberalis have, which hormone do these receptors bind, and which endocrine organ produces this hormone?

Answer 7

melatonin receptors for melatonin, a neuropeptide produced by the pineal gland (epiphysis cerebri)

Question 8

what are the cells of the pars intermedia called and which hormone do they secrete?

Answer 8

melanotrophs; produce POMC, a precursor to several hormones, including alpha-melanocyte stimulating hormone (MSH)

Question 9

list the 2 types of acidophils and 3 types of basophils that populate the pars distalis, list the hormones they produce, and list the effect of the hormone on the target organ

Answer 9

acidophiles:
somatotropes: secrete growth hormone
lactotropes: secrete prolactin

basophils:
thyrotropes: secrete TSH
gonadotropes: secrete FSH and LH
corticotropes: secrete ACTH