1. State University of Medicine and Pharmacy “Nicolae Testemitanu”
LIVER
GALL BLADDER
PANCREAS
Department of Histology, Cytology and Embryology
Tatiana Globa

2. The Liver
 Largest gland of the body
 Two principal lobes: right and left
 Right lobe further subdivided:
Quadrate lobe and caudate lobe
 Is surrounded by a capsule of connective tissue
(Glisson’s capsule).

4. Functions of the Liver
Digestive and Metabolic Functions
 synthesis and secretion of bile
 storage of glycogen and lipid reserves
 maintaining normal blood glucose, amino
acid and fatty acid concentrations
 synthesis and release of cholesterol bound
to transport proteins
 inactivation of toxins
 storage of iron reserves
 storage of fat-soluble vitamins

5. Functions of the Liver
Non-Digestive Functions
 synthesis of plasma proteins
 synthesis of clotting factors
 synthesis of the inactive angiotensinogen
 phagocytosis of damaged red blood cells
 storage of blood
 breakdown of circulating hormones (insulin
and epinephrine) and immunoglobulins
 inactivation of lipid-soluble drugs

6. The morpho-functional unit of
the liver
 “classical liver lobule”
 portal lobule
 liver acinus

8. LIVER LOBULE
Hexagonal-shaped liver
lobule (classical lobule) is
the traditional description
of the liver parenchyma
organization
 Composed of hepatocyte
(liver cell) plates(cords)
radiating outward from a
central vein
 Between the plates of
hepatocytes there are
sinusoids
 Has a central vein
 Portal triads are found at
each of the six corners of
each liver lobule

11. Sublobular vein
Distributing vein
Central vein
Plates of hepatocytes

12. PORTAL TRIADS
Portal triads (also called portal areas or portal
canals) are located at the corners of liver lobules.
Each portal area contains three (hence the term
portal triad) more-or-less conspicuous tubular
structures all wrapped together in connective
tissue.
 a branch of the bile duct
 a branch of the portal vein - interlobular vein
 a branch of the hepatic artery - interlobular
artery

14. Hepatocytes
 are cuboidal cells with one or
two large euchromatic nuclei
and with abundant, grainy
cytoplasm that stains well
with both acid and basic dyes
(reflecting the abundance of
various cellular constituents).
 they may accumulate
abundant lipofuscin (yellow-
brown "wear-and-tear"
pigment), especially with
advancing age.
 a typical hepatocyte has two
surfaces with microvilli

15. Hepatocyte
ultrastructure
• all cytoplasmic
organelles are
very well
developed
• cell membrane
facing a bile
canaliculus
and the
perisinusoidal
space forms
microvilli

16. Hepatocytes are located in flat irregular plates (cords) that are
arranged radially like the spokes of a wheel around a branch of the
hepatic vein, called the central vein or central venule since it really
has the structure of a venule. Each hepatic plate contains 2 rows of
hepatocytes. Between 2 rows of hepatocytes of the plate there is bile
canaliculus. Between the plates of hepatocytes there are sinusoids
capillaries.

18. Bile canaliculus
Hepatocytes form
2 rows
Sinusoid
Space of Disse
Hepatocytes
Microvilli

19. Sinusoids capillaries
 are larger than conventional capillaries and less regular in
shape. They are lined by thin endothelial cells and lacks a
basement membrane (is absent over large areas except the
periphery and center of the hepatic lobule)
 Also residing on the sinusoidal walls are macrophages called
Kupffer cells. These are phagocytic cells that remove
particulate material and old red blood cells from circulation.
Kupffer cells are members of the mononuclear phagocyte
system.
 Pit cells are attached to the Kupffer’s cells. These cells
contain granules and they are like large lymphocytes, killer
cells. They make an anticancer effect.
 The space between the fenestrated endothelium and the cords
is named the space of Disse.

22. sinusoid
sinusoid
Kupffer cell

23. Perisinusoidal space (space of
Disse)
It contains
 microvilli of hepatocytes,
 blood plasma,
 processes of the Kupffer’s cells
 lipocytes (adipose cells, commonly called an Ito cells).
They are located between some hepatocytes. These cells
have been shown to be the primary storage site for
vitamin A. They also can produce connective tissue fiber
in the large amount at the cirrhosis.
 In the fetal liver, the space between blood vessels and
hepatocytes contains islands of blood-forming cells.

24. sinusoid
Lipid inclusions Ito cell

25. The blood circulation through the
liver
 System of inflow: the liver receives blood from the hepatic artery
(supplies oxygen-rich blood to the liver) and portal vein (carries
venous blood with nutrients from digestive viscera). They branch
into lobar, segmental, interlobular, distributing branches.
 System of circulation: the distributing branches of vessels
contribute blood to the sinusoids which provide the exchange of
substances between the blood and liver cells. Sinusoids contain the
mixed blood.
 System of outflow: sinusoids drain blood from the periphery of
the classical hepatic lobule toward its center, into the central vein.
Outside hepatic lobules central veins drain into the sublobular
(intercalated) veins, which join 3-4 together and drain into the
hepatic vein. It drains into the inferior vena cava.

27. GALL BLADDER
functions
 storage of bile
 concentration of bile
 acidification of bile
 send bile to the duodenum in response to
cholecystokinin
secreted by from enteroendocrine cells in
small intestine

29. Tunics (layers) of the Gall Bladder
 TUNICA MUCOSA: When the gall bladder is empty, this layer is
extremely folded. When full, this layer is smoother but still has some
short folds.
 lamina epithelialis: composed of simple columnar epithelial cells
with numerous microvilli on their luminal surfaces and connected
by tight junctions near luminal surfaces.
 lamina propria: composed of loose connective tissue rich in
reticular and elastic fibers to support the large shape changes that
occur in the lamina epithelialisl; lamina propria may contain
compound tubuloalveolar glands. May be mucous or serous.
 lamina muscularis mucosae: not present
 TUNICA SUBMUCOSA: present and typical
 TUNICA MUSCULARIS: contains much smooth muscle, poorly
organized
 TUNICA SEROSA: present and typical

33. Pancreas
 Exocrinegland (97%)– PROENZYMES for digestion
of carbohydrates, proteins & fats (amylase, trypsin,
lipases)
 Endocrine
gland (3%)– INSULIN and GLUCAGON
(carbohydrate metabolism)

35. The exocrine pancreas
 The exocrine portion of the pancreas is a
compound acinar gland
 It has many small lobules, each of which is
surrounded by connective tissue septa
through which run blood vessels, nerves,
lymphatics, and interlobular ducts.
 Exocrine secretion by the pancreas is
controlled by hormones and nerves.

38. The exocrine pancreas
 Acini: The secretory cells of the pancreas are arranged around
Acini
a small lumen.
 The pancreatic acinar cells are highly active in protein
synthesis for export and this high activity is reflected in their
bizonal staining properties. The basal region of these secretory
staining
cells usually stains intensely with hematoxylin reflecting the
presence of large amounts of endoplasmic reticulum where the
protein is being synthesized on ribosomes – homogen zone.
The presence of numerous zymogen granules containing high
concentrations of protein is reflected in the intense eosin
staining in the apical region of the secretory cells – zymogen
zone. These granules are most abundant during fasting or
between meals and least abundant after a meal has been
ingested.

40. Centroacinar
cell
These cells
form the first
part of the
intercalated
Zymogen duct
granules

41. The exocrine pancreas
 Ducts: The secretory product of the acinar cells is carried out
of the pancreas by a duct system as in other exocrine glands.
 The first part of the duct system is called the intercalated
The first part of the duct system is called the
duct or intralobular duct. It is lined with cuboidal epithelial
cells that secrete bicarbonate ion into the secretory product.
This duct actually extends into the acinar lumen, where its
walls consist of the pale staining centroacinar cells.
walls consist of the pale staining
 Intercalated ducts have very little connective tissue around
them but they lead into larger interlobular ducts which lie
them but they lead into larger
within more prominent connective tissue septa. Interlobular
ducts are lined with a low columnar epithelium that may
contain goblet cells. Interlobular ducts empty into the main
pancreatic ducts that exit the pancreas.

44. Pancreatic juice
 trypsin,chymotrypsin and carboxypeptidase
hydrolyse proteins into smaller peptides or
amino acids;
 ribonuclease and deoxyribonuclease digest the
corresponding nucleic acids;
 pancreatic amylase digests carbohydrates;
 pancreatic lipase digests lipids;
 cholesterol esterase breaks down cholesterol
esters into cholesterol and a fatty acid.

45. The endocrine pancreas.
 The cells of the
endocrine portion of the
pancreas are arranged
either in round-to-oval
shaped areas rich in
blood vessels known as
the islets of
Langerhans or they
may be scattered
throughout the exocrine
portions of the pancreas
near the acini or ducts.

46. Island of Langerhans
• β-cells (75%) which secrete insulin (stimulates the synthesis of
-cells
glycogen, protein and fatty acids; facilitates the uptake of glucose into
cells; activates glucokinase in liver cells). They are located in the central
part of the island.
• α-cells (20%) which secrete glucagon (effects opposite to those of
-cells
insulin). They are generally located peripherally in the islets.
• δ-cells (5%) which secrete somatostatin, a locally acting hormone which
-cells
inhibits α -, β-cells.
•a few other endocrine cells, which secrete
• pancreatic polypeptide, which stimulates chief cell in gastric glands,
inhibits bile and bicarbonate secretion – PP-cells,
PP-cells
• vasoactive intestinal peptide (VIP), which has effects similar to
glucagon, but also stimulates the exocrine function of the pancreas
and decrease the arterial blood pressure – δ1-cells,
1-cells
• secretin, which stimulates the exocrine pancreas, and motilin, which
increases GIT motility – EC-cells (enterochomaffin cells).
EC-cells

47. Islet of Langerhans