Pituitary, Pineal, and some Thyroid Flashcards
common features of endocrine organs
parenchyma = cords or clumps of hormone producing cells
highly vascular = fenestrated capillaries
ductless glands (not exocrine)
secretes hormones = peptide, amino acids derivatives, or steroids
adenohypophysis
anterior pituitary gland
glandular tissue (adeno-)
more cellular than posterior (darker staining)
origin = ectoderm from roof of mouth
neurohypophysis
posterior pituitary
neural secretory tissue
lighter staining = mostly axons
origin = ectoderm from floor of brain
divisions of anterior pituitary
pars distalis
pars tuberalis
pars intermedia
divisions of posterior pituitary
median eminence
infundibulum
pars nervosa
chromophils
cells that stain alot
cells that make and secrete pars distalis hormones
chromophobes
do not take up dye….in pars distalis
folliculostellate cells
non secretory cells in pars distalis
unknown function
acidophils
pink staining cells in H&E stain and orange in PAS stain
secrete GH and prolactin from pars distalis
basophils
purple staining cells in H&E and PAS stains
secrete FSH, LH, TSH, and ACTH from par distalis
superior hypophyseal artery
need to provide arterial blood to organ to provide O2
remove waste products, and to bring nutrients to tissue itself
branches out into meshwork of fenestrated capillaries surrounding the hypothalamus
how do RFs get from hypothalamus towards pars distalis
superior hypophyseal artery
within capillary meshwork…the termini of neuroendocrine cells that release RFs
pathways of RFs to pars distalis
- capillary meshwork around hypothalamus
- plexus collapses down into portal veins (hypophyseal portal veins)
- releasing hormones shunted down into secondary capillary plexus which open up portal veins into meshwork of fenestrated capillaires surrounding millions of acido and basophils
- stimualtes relase of pars distalis hormone
- drain out by hypophyseal veins
RFs are usually broken down by what after stimulate target cell
internalized and broken down by lysosomes into amino acids
what artery infuses the pars nervosa
inferior hypophyseal artery
pars intermedia
cuboidal cells and colloid containing cysts (remnants of Rathke’s pouch)
secretes MSH (melanocyte stimulating hormone) --> stimulates melanin production in lower animals
pars nervosa
unmyelinated axons and pituicytes (supportive glial like cells)
where are oxytocin and ADH made
made in separate neurons whose cell bodies are located in both the PVN and SON
neuroendocrine cells will either make ADH or oxytocin….but not both at the same time –>they are mixed up in the PVN
neurophysin
carrier hormone for oxytocin and ADH
ADH staining
stain in the PVN in the hypothalamus and the posterior pituitary gland in the Herring Bodies
Pineal Gland stroma
CT capsule (pia mater) and septae that divide the gland into lobules
fenestrated capillaries
corpora arenacea = brain sand = calcified concretions
pineal gland parenchyma
90% of cells = pinealocytes
- arranged in clumps and cords within lobules
1 or 2 elongated cell processes at the end in association with capillaries
produce melatonin during periods of dark
intersitial cells = glial like cells
melatonin
produced by pineal gland cells
secreted during dark phase of light/dark cycle
involved in circadian and seasonal biorhythms
antigonadal effect in rats
antiproliferative effects on rbeast and prostate canacers
has an effect on downplaying the gonads
melatonin regulation of secretion
innervation of postganglionic sympathetics form the superior cervical ganglion
axons synpase on the pinealocytes and control the production of melatonin
Thyroid gland structure
fibroelastic CT capsule and septae
strome =reticular cells and reticular fibers
highly vascular with fenestrated capillaries
cannot remove thryoid glands without also removing parathyroid glands
thyroid follicle
structural unit of gland lined with follicular cells (squamous to low columnar)
pre hormone is stored in colloid
parafollicular cells vs follicular cells
parafollicular cells = calcitonin
follicular cells = T3 and T4
EM of follicular cells
losts of RER, golgi, and lysozymes
where does TSH bind
basal side of follicular cells
