Sept11 M2-Histo_Pituitary_Gland_Mammary_Gland Flashcards
glands in embryo
- form from endoderm and ectoderm
- lining of columnar epithelial cells undergoes induction from adjacent tissues or neural cells (tube)
- eptih proliferates and invaginates
glands in embryo: 2 things that can happen after epith invagination
- secretory portion at end (base) stays connected to duct and surface lumen
- duct deteriorates, cells die. mass of secretory cells is now separate
glands in embryo: 2 things that can happen to separated mass of secretory cells
- cells organize into cords (like in pituitary) assoc with fenestrated caps system with fenestrated endoth cells
- endocrine cells organize into follicules (like in thyroid) surrounded by fenestr capillaries
development of exocrine glands (mammary, salivary, pancreas)
- ducts form and split into smaller acini with end glands
- formation of several lobes in mammary gland, subdivided into lobules by CT
- duct system is intralobular (in lobules) or interlobular (out of lobules, between them)
cords of anterior pit
- cells assoc with capillaries called sinusoids (large caps)
- cords ass with caps, embedded in CT
follicle def (like thyroid)
circle of cells with follicular secretion in middle (like colloid with TH)
pit gland embryo dev
- invagination of ectoderm at base of mouth (for ant pit)
- floor of diencephalon also produces an invagination (for post pit)
- both come together to form the pit
- duct system from mouth detaches from invagination of ectoderm to leave the ant pit alone attached to post pit
parts of pit
- pars nervosa (post pit)
- pars distalis (ant end of ant pit)
- pars tuberalis (ant pit part in middle, on top of both ant pit and post pit, surrounds the infundibulum)
- pars intermedia (ant pit part close to post pit. = most post part of ant pit)
pit dev relation to bone
- bone forms mesenchymal tissue around
- bone depression (sera pulsica) where ant pit and post pit go)
pars intermedia is a remnant of what embryo structure
Rathke’s pouch
ant pit vs post pit on histo
ant pit is darker
what do you see in pars intermedia
cysts
zone of attachment of post pit (neurohypophysis) to hypoth
median eminence
nuclei of hypoth going into median eminence to post pit
- supraoptic nuclei
- paraventricular nuclei
- send long axons penetrating the infundibulum, the median eminence and then PN*
2 arteries supplying pituitary
- superior pit artery
- inferior pit artery
what sup pit artery does
- supplies infundibulum (pituitary stalk = connection between ant pit and post pit) and PT a bit
- makes a rich cap network called primary capillary plexus (found in the MEDIAN EMINENCE)
- portal veins connect primary cap plexus to a secondary cap plexus that is in the ant pit
supraoptic and PV nuclei of hypoth (to post pit) are in what part of hypoth
posterior part. are dorsal nuclei
ventral nuclei of hypoth are what nuclei + do what
- are the ventral medial nuclei, the infundibulary nuclei and the dorsal medial nuclei**
- send long axons to the infundibulum and pars tuberalis for the ant pit
- produce neurosecretory hormones regulating ant pit
main categories of cells in ant pit
- chromophils (stain) and chromophobes (don’t stain) (resting, degranulated cells)
- folliculostellate cells
chromophils subtypes
- acidophils (stain with eosin)
- basophils (bind hematoxylin)
2 kinds of acidophils (can’t distinguish on EM)
- somatotrophs
- mammotrophs (lactotrophs)
somatotrophs fct
- make somatotropin (GH)
- GH goes to liver to make it produce somatomedins (insulin like growth factors 1 and 2)
- IGF1 and IGF2 go to epiphyseal plate of bone to promote elongation by chondrocytes
what hypoth releasing hormones from ventral nuclei controls somatotrophs
- somatotropin releasing hormone (SRH) (or GHRH). stimulates GH release
- somatostatin (inhibits GH release so called GH inhibiting hormone or GHIH)
mammotrophs (lactotrophs) do what
produce prolactin
what hypoth hormones from ventral nuclei control lactotrophs (mammotrophs)
- PRH (prolactin releasing hormone). stimulates its release
- dopamine (or prolactin inhibiting factor = PIF). inhibits its release
what hormone from elsewhere in the body stimulates prolactin release by mammotrophs
oxytocin
3 categories of basophils
- corticotrophs
- tyrotrophs
- gonadotrophs
corticotrophs fct
- secrete ACTH
- secrete LPH (lipotropic hormone)
- secrete POMC
what ventral hypoth hormone stims corticotrophs to release ACTH
-CRH (corticotropin releasing hormone)
thyrotrophs fct
make TSH (thyroid stimulating H) (thyrotropin)
what ventral hypoth hormone stims thyrotrophs to release TSH
TRH (thyrotropin releasing H)
gonadotrophs fct
- make LH (stims formation of CL in female. stims Leydig cells to make testo in male)
- make FSH
what ventral hypoth hormones control gonadotropin release by gonadotrophs
- GnRH (for FSH and LH)
- LHRH (for LH)
where GnRH and LHRH are produced specifically
in ventral hypoth nuclei at level of infundibulum
folliculostellate cells fct
-nonsecretory, support secretory cells, support the cords
what are the cysts in the pars intermedia
colloid surrounded by cuboidal cells
significance of cuboidal cells of PI cysts in animals
produce POMC which forms MSH which stimulates melanocytes
in humans, saw that POMC comes from corticotrophs
POMC fct in humans vs animals
- animals = stim melanocytes
- humans = not this. have another fct
pars nervosa histo
- mostly axons from PV and supraoptic nuclei
- end in small dilations called Herring body which contain vasopressin and oxytocin
AVP fct
- water retention
- conc of urine
oxytocin fct
- stim contraction of SM of uterus
- contract myoepithelial cells of mammary glands during lactation
nuclei found in PN are what
- nuclei of capillaries of the primary plexus (that was over the median eminence)
- nuclei of pituicytes
pituicytes def
cells in PN (post pit) that are supportive cells
pituitary adenoma def
benign tumor of pituitary producing excess nbr of acidophils or basophils
pituitary adenoma of somatotrophs consequence in children (open growth plate)
gigantism. too much GH made = growth of cartilage in length
pituitary adenoma of somatotrophs consequence in adults (closed growth plate)
acromegaly because of growth of periosteal bone
separations in mammary gland (exocrine)
- lobes and lobules
- main duct
- interlobular duct
- intralobular duct
- secretory portion
how many glands in the breast
15-20. and each gland is a lobe so 15-20 lobes
name of main duct + histo in whole portion except near nipple
lactiferous duct
-2 layers of cuboidal stratified epith, remnant of sweat glands
main duct histo near nipple
squamous stratified epith
cells producing milk in the secretory portion
alveolar cells
milk components
proteins, lipids, lactose (all made by alveolar cells)
2 mechanisms of milk secretion
- merocrine
- apocrine
2 states of mammary glands
- resting (nonsecreting)
- lactating (active)
does the male mammary gland has the same histo as female resting mammary gland
no because at puberty, excess E and P in female make mammary glands develop
structure of resting mammary gland
- lactiferous duct (double cuboidal epith on BM)
- smaller ducts (double cuboidal epith) (interlobular even though no lobules)
- no lobules
structure of lactating gland
- now have lobules
- interlobar CT
- lactiferous and interlobular duct same as resting but the interlobular duct now has a simple cuboidal epith at its end
- intralobular ducts (simple cuboidal epith)
- alveoli (circular, 1 layer of cuboidal cells) (secretory portion: always caps nearby)
inter vs intralobular duct
- interlobular surrounded by lot of CT
- intralobular not lot of CT around
how mammary glands dev during pregnancy
- T1: ducts elongate and form buds at their ends
- T2: buds grow and multiple and form primitive acini
- T3: alveoli produce a lumen with lymphoid cells and lipid droplets initially called colostrum and eventually replaced by milk
mammary alveolar cells charact on EM
- polarized. basal and apical (lumen) plasma membrane
- secretory
- attached to BM
- Golgi packing material from ER and making secretory vesicles containing casein (a protein), lactoalbumin (albumin+sugar) and lactose (sugar)
how lipid droplets are formed in alveolar cells by merocrine secretion
- the membrane forms lipid droplets
- the droplets coalesce and form larger lipid droplets
- large droplets eventually push the plasma membrane and detach with a small area of cytoplasm surrounding them
meaning of word merocrine
doesn’t modify the structure of the secretory cell
apocrine secretion def
substantial loss of cytoplasm when lipid micelle (droplet) is secreted in the lumen
contents of merocrine secretion
lactose, casein, albumin
contents of apocrine secretion
lipids
other fct of mammary alveolar cells
- take Igs from capillary system using Rs
- internalize the basal membrane with Ig-R
- vesicles transcytose from basal membrane to apical membrane and release Ig in the milk
- Igs as passive defense mechanism for the baby*
one of most common form of cancer in mammary glands
ductal CA (from ductal cells) -can enter in cap system and metastasize via lymphatics to lung and brain
acute mastitis def
infection (or infection + occlusion) of the ducts in the lactating or involuting (regressing) the mammary glands
