Histology of glands Flashcards
what are glands formed from
epithelial tissue
subdivisions of glands
endocrine
exocrine
endocrine glands
secrete hormones directly into the blood stream
thyroid gland
exocrine glands
release their substances either directly onto an epithelial surface e.g. goblet cell in the gut
OR via a system of ducts e.g. major salivary glands
how do glands develop
from a lining or covering epithelium by invagination into the underlying connective tissue
location of thyroid gland
anterior neck with right and left lobes
connected to an isthmus
cell arrangement thyroid glands
arranged into spherical structures called follicles
thyroid hormones are stored here
each follicle is lines with single layer of follicular cells which are cuboidal epithelium and surrounded by reticular fibers
vascular capillary netwrok surrounds the follicles for entrance of thyroid hormones into the bloodstream
follicles in thyroid gland
structural and function units of the gland
in active follicles the epithelium is cuboidal
less active follies the epithelialcellr appear flattened
all follicles are fixed with colloid
what divides the thyoird gland into lobules
connective tissue septa from the capsule of the thyroid gland
they extend into the glands interior and divide the gland
what is found between individual follicles in the thyroid gland
small amount of inter follicular connective tissue
what is in the image
thyroid gland
colloid in thyroid
is composed of thyroglobulin
it is inactive iodinated glycoprotein compound for storage of thyroid hormones
stain pink
by itself doesnt have any hormonal activity
parafollicular cells/ C cells in thyroid
pale staining
found peripherally in basal lamina of follicular epithelium or as clusters between follicular cells
secrete calcitonin
calcitonin function
inhibit bone resorption by inhibiting osteoclast activity
lowers blood calcium levels
when necessary what do follicular cells do to stored thyroglobulin in thyroid
can take up the stored substance
transport it across the epithelium
release thyroid hormones into capillaries surrounding the follicle
what does thyroglobulin contain
modified tyrosine amino acids that constitute the thyroid hormones:
thyroxine (tetraiodothyronine,T4) and triiodothyronine T3
label the image
principal cells in thyroid
line the follicles
simple cuboidal epithelium
what is the pituitary gland controlled by
the hypothalamus of the brain
regulatory hormones are transported to the pituitary gland
embryonic origins of the pituitary
Adenohypophysis
neurohypophysis
clinical divisions of the pituitary gland
anterior lobe
posterior lobe
where is the pituitary gland located
what does the adenohypophysis contain
pars distils
pars tubercles
what does the neurohypophysis contain
pars intermedia pars nervosa
infundibulum/ pituitary stalk
where is the neurohypophysis derived from
down growth of nervous tissue from hypothalamus
it remains joined by the pituitary stalk
what is contained within the posterior pituitary/neurohypophysis
hypothalamohyphophyseal tract
consisting of axons from neurons whose cell bodies are located in the supraoptic and paraventricular nuclei of the hypothalamus
where does the anterior pituitary arise from
arises as an epithelial/ectodermal upgrowth from the roof of the primitive oral cavity known as Rathkes pouch
describe internal structure of Aden-hypophysis
may contain a cleft or group of cyst like spaces which represent the vestigial lumen of rattles pouch
dividing the major part of anterior pituitary form Thun zone of tissue against posterior pituitary known as pars intermedia
pars intermedia location
within the Aden-hypophysis but classified as posterior pituitary
pars distils
95%
forms anterior wall of rattles pouch
pars intermedia
forms posterior wall of rathkes pouch with pars nervosa of neurohypophysis
pars tuberalis
forms collar of cells around the infundibulum of the neurohypophysis
hormones secreted by posterior pituitary
antididiuretic hormone (aka vasopressin) and oxytocin
synthesises in the neurone cell bodies of supraoptic nucleus
what do ADH hormones act on
act directly on non-endocrine tissues
where is ADH specifically made
synthesises in the neurone cell bodies of supraoptic nucleus
where is oxytocin specifically made
paraventricular nucleus of the hypothalamus
how do ADH and oxytocin get to posterior pituitary
bound to glycoproteins
they pass down the axons of the hypothalamopituitary tract
through the pituitary stalk
to posterior pituitary where they are stored in distended terminal parts of axons
release of posterior pituitary hormones
controlled directly by nervous impulses passing down the axons from the hypothalamus
called neurosecretion
neurohypophysis
hypothalamic supraoptic and paraventricular nuclei consist of vasopressin and oxytocin synthesising hormones
send projections here
where in brain does the pituitary gland sit
in body depression in the sphenoid bone
called sella turcica
label the image
PP posterior pituitary
AP anterior pituitary
H hypothalamus
P pituitary stalk
V third ventricle
O optic chiasma
pars tuberalis
surrounds the infundibulum
infundibulum
connects hypothesis with hypothalamus at base of the brain
cell types within the pars distils
chromophobe cells, don’t take H&E
chromophil cells
chromophil cells
subdivided into acidophils (alpha cells)
and basophils (beta cells)
pars nervosa
consists primarily of unmyelinated axons and supporting pituicytes
what surrounds pars distils and pars nervosa
connective tissue capsule
what supplies the pars distils and pars nervosa
blood vessels and capillaries
label the image
what are all of the specific cell types in pituitary
somatotrope
mammotrope
thyrotrope
gondadotrope
andrenocorticotrope
cell types in pars distalis
somatotrope
mammotrope
thyrotrope
gondadotrope
andrenocorticotrope
pars tuberalis cell types
gonadotropes only
pars intermedia cell types
contain basophils
but secretions in humans are unclear
although ACTH secretion is possible
acidophils
hormone containing granulesin cytoplasm
stain with acidic dies e.g. eosiin
basophils
hormone containing granules in cytoplasm
stain with basic dyes e.g. hematoxylin
somatotrope
acidophil
secretes GH
mammotrope
acidophil
secretes prolactin
thyrotrope
basophil
secretes TSH
gonadotrope
basophil
secretes FSH/LH
adrenocorticotrope
basophil
secretes ACTH
where are oxytocin and vasopressin stored
in herring bodies in pars nervosa
pituicytes
glial cells of posterior pituitary
assits in storage and release of neurohypophysial hormones
what is in the image
herring bodies
location of adrenal gland
superior pole of each kidney
surrounded by dense irregular connective tissue capsule and embedded in adipose tissue around kidneys
contents of secretory portion of adrenal gland
outer cortex and inner medullar
aka
mesoderm and neural crest
linked buy common blood supply but have distinct origins structures and functions
cells in Cortex brief adrenal
steroid secreting
cells in medulla of adrenal
chromaffin
subdivisions of the adrenal gland
zona glomerulosa
zona fasciculata
zona reticularis
zona glomerulosa
located immediately beneath capsule
cells arranged in round clusters
secretes mineralocorticoids, aldosterone
zona fasciculata
middle layer, largest cortical zone
cells arranged in rows, perpendicular to capsule alternating with wide diameter, fenestrated capillaries
secretes glucocorticoids and androgens
zona reticularis
forms deepest layer of the cortex
cells arranged as anastomosing cords
same secretions as zona fasciculata: glucocorticoids and androgens
what is the secretion of glucocorticoids controlled by in the adrenal gland
ACTH
released from Aden-hypophysis
chromaffin cells
synthesise and release epinephrine and norepinephrine
image of the adrenal gland
label the image of the adrenal gland
zona glomerulosa
zona fasciculata
zona reticularis
ZF is middle zone and composed of pale staining cells rich in lipid droplets
pancreas location
in the curve of duodenum
divided into head body and tail
type of gland is the pancreas
exocrine and endocrine
exocrine pancreas
produces alkaline secretion containing digestive enzymes
empties into the duodenum
endocrine pancreas
secretes insulin, glucagon and somatostatin
regulate blood glucose levels
pancreas connective tissue
thin capsule
septa extend from
covers larger vessels and ducts
separates parenchyma into lobules
islets of langerhans
clumped masses of pale staining endocrine cells
embedded in exocrine acinar tissue of pancreas
predominant cell types in endocrine pancreas
alpha cells
beta cells
delta cells
alpha cells pancreas
secretes glucagon
elevates glucose levels in the blood
converts glycogen to glucose
located peripherally
beta cells pancreas
secretes insulin
lowers blood glucose levels
converts glucose to glycogen
most numeras and central
delta cell
secretes somatostatin
inhibits Hal secretion from parietal cells
scattered and less abundant
what is in the image
I= islets of langerhans
C= fibrocollagenous capsule
exocrine pancreas detail
compound acinar gland
acinar cells secrete numerous digestive enzymes that break down proteins, carbohydrates and lipids
ducts begin as centroacinar cells located in acini
intercalated ducts and interlobular ducts
intercalated ducts
lined with low simple squamous epithelium that secrete HCO3
interlobular ducts
lead into one or more excretory ducts
empty into the duodenum
relevance of HCO3 secretion
to neutralises acidity of chyme entering duodenum
what is each acinus drained by
short intercalated duct of simple squamous or low cuboidal epithelium
initial cells of these small ducts extend into the lumen of acinus as small pale staining centroacinar cells unique to pancreas
exocrine pancreas image
intercalated ducts merge with interlobular and larger interlobular
before joining main pancreatic duct
cortex summary
medulla summary
pancreas summary
thyroid gland summary
parathyroid gland summary
exocrine glands and ducts
secretory products released onto and external or internal epithelial surface
either directly via a duct or a duct system
classified into unicellular such as goblet cell or multicellular glands
multicellular glands classification
based on presence of tubule and acini presence
configuration of the duct if it is simple or compound
examples of simple glands
simple tubular
simple coiled
simple branched tubular
simple alveolar (acinar)
simple branched alveolar
examples of compound glands
compound tubular
compound alveolar (acinar)
compound tubuloalveolar
simple tubular
no duct
simple coiled tubular
simple branched tubular
simple alveolar
simple branched alveolar
compound tubular
compound alveolar
compound tubuloalveolar
different types of cell secretions
merocrine
apocrine
holocrine
merocrine
Secretory product is released by exocytosis of contents contained within membrane-bound vesicles. E.g., pancreatic and parotid gland secretions.
apocrine
Secretory material is released in an intact vesicle along with some cytoplasm from the apical region of the cell. E.g., mammary gland secretions.
holocrine
Entire cell is released during the secretory process. E.g., sebaceous glands.
salivary glands
parotid
submandibular
sublingual
duct system
serous acinus
basally located round nucleus
mucous acinus
basally located flat nucleus
serous demilune
half moon shaped serous cells at distal end of mucous secretory unit of mixed salivary glands (submandibular or sublingual)
my-epithelial cells
cells that contract to release secretion from acini to duct
parotid duct system
serous only
type of duct system submandibular and sublingual
mixed glands with serous demilunes
as processes of my-epithelial cells contract they compress acinus and facilitate release of secretary product into gland duct
pattern of the duct system
secretary
intercalated
striated
interlobular
lobar
main duct
lining of intercalated ducts
simple squamous to cuboidal
lining of striated ducts
simple cuboidal to columnar
lining of interlobular ducts
formed by anastomosis of striated ducts and have epithelia from simple columnar to stratified columnar
excretory duct lining
stratified epithelium
becomes stratified squamous prior to junction with epithelium of oral cavity
parotid gland
what is in the image
parotid gland
T= septa
Ac= acini
SD= striated ducts
secretion from parotid gland
Serous in nature. Thin, watery, protein secretion. Nucleus is round and basally located.
submandibular gland
secretion from submandibular gland
The submandibular salivary gland secretes a mixed serous/mucous product. Mucus. Thick, viscous, glycoprotein secretion. Nucleus is flattened and located in the base of the cell.
submandibular ducts
what is in the image
label the image
SAc – Serous acini
SeD – Serous demilunes
MA – mucous tubules
SD – Striated duct
