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Histology: Liver & Gallbladder (Liver (tissues (perisinusoidal spaces,…
Histology: Liver & Gallbladder
Liver
tissues
parenchyma
monolayer plates of hepatocytes (~95%)
stroma
CT w/ vessels, nerves, lymphatics, bile ducts
sinusoids
spaced b/w plates (portal triads to central vv.)
discontinuous endothelium
Kupffer cells
mononuclear phagocytes; filter blood >> lymph (bacteria, toxins, parasites, aging RBCs)
hemosiderosis/hemochromatosis
: iron deposits w/in
round, ovoid shape
basal lamina absent in large areas
large fenestrae
wider than capillaries
perisinusoidal spaces
"Spaces of Disse"
b/w sinusoidal endo & hepatocytes
incomplete barrier >> free flow of proteins
blood forming colonies
exist in developing fetus
present in adults w/ chronic anemia
Ito cells
"hepatic stellate cells"
vitamin A storage (or fat)
can differentiate into myofibroblast >> fibrogenesis >> collagen formation (diseases such as chronic inflammation or liver cirrhosis)
contain: 2% Kupffer, 1% Ito, & 2% endothelial cells
structure
3 models of liver organization & fxn
schematic
classic (hepatic) lobule
separated by sinusoids
blood from portal vv. & hepatic aa. >> central v.
hexagonal stack of parenchyma
portal canals at each corner & central v. at center
portal lobule
bile flow: central vv. >>
portal canal
(opposite blood)
made of stroma
portal triad
portal v.
largest, thin wall
hepatic a.
thicker, arteriolar wall
sends blood to central v.
bile duct
simple cuboidal or columnar epi
lymphatics
thinnest wall, often collapsed
@ angle of hexagon
connects 3 central vv.
correlates w/ exocrine fxn (bile production & flow)
axis = an interlobular bile duct of classic lobules
liver acinus
lozenge-shaped
best correlates blood perfusion & liver pathology
zones
II
: middle
III
:
farthest from blood supply, near central v.
least oxygenated
most detoxification >> least healthy cells
I
:
closest to blood supply, near portal canal
most oxygenated
healthiest cells
cell death & lipid accumulation can occur in Zone I first
Pt w/ CHF
smaller functional unit of lobule
connects 2 central v. & 2 portal canals
hepatocytes
H&E
large, polygonal
nucleus
many binucleate
distinct heterochromatin clumps
2 nucleoli
large, central
cytoplasm
acidophilic (pink)
glycogen w/ PAS
stains magenta
lipid droplets (variable)
increase w/ exposure to hepatotoxins (ethanol)
peroxisomes w/ immunohisto (large & numerous)
80% of cell population
life span of 5 months; liver capable of regeneration
biliary tree
system of channels for bile
cholangiocytes
cuboidal >> columnar epi
complete basal lamina & tight jxns
apical microvilli
one primary cilium (senses changes in bile flow >> cholangiocyte secretion)
bile canaliculus
grooves on adjacent hepatocytes
closest to central v.
Canal of Hering
hepatocytes & cholangiocytes
contractile activity
may contain hepatic stem cells
bile ductule
only cholangiocytes
bile duct
portal triad
L & R hepatic ducts >> gallbladder
increases in diameter from bile canaliculus >> bile duct
Gallbladder
pear-shaped, blind-ending sac
layers
mucosa
simple columnar epi
apical microvilli
tight jxns
~absorptive intestinal cells
many mitochondria
lamina propria
fenestrated capillaries
highly cellular (plasma cells & many lymphocytes)
no lymphatic vessels
mucous-secreting glands w/in neck region
plasma cells
ABSENT muscularis mucosa
many folds
ABSENT submucosa
muscularis externa
smooth m. bundles (randomly oriented)
contraction >> contents into cystic duct
collagen & elastic fibers
Rokitansky-Aschoff Sinus (RAS)
d/t hyperplasia >> herniation of epi cells thru ME
site of bacterial accumulation
predispose to gall stones
adventitia
dense CT w/ adipose tissue
large vessels, lymphatics & ANS nerves
serosa when not attached to liver