3. Introduction
The pancreas is a compound tubuloacinar, lying
behind the stomach and extending transversely from
the spleen to the loop of duodenum.The head is
joined to the body of the gland by slightly constricted
part neck.The body becomes narrow,tapering into tail.
Pancreas is a duplex gland .i.e. it has both exocrine
and endocrine parts.
Exocrine portion consists of twp ducts, the longer
main pancreatic duct or duct of wirsung and shorter
duct or duct of santorini.
These ducts carry the pancreatic juice in duodenum
which contains several digestive enzymes like
trypsin,amylase and lipase.
4. Introduction continued…
Inside the substance of pancreas there are
groups of specialized cells surrounded by
connective tissue, which form the endocrine part
of the gland.
These cells are called islets of Langerhans.
Islets of langerhans secrete two hoprmones ,
insulin and glucagon.
Insulin plays important role in carbohydrate
metabolism while glucagon causes elevation of
blood sugar.
7. Microscopic structure continued….
The pancreas has a thin cover of loose
connective tissue from which septa pass into the
gland, subdividing it into many small lobules.
Each lobule is again composed of several
rounded or tubular groups of pancreatic cells
called acini.
Among the acini are the scattered the islets of
langerhans.
The acini cells form the parenchyma of the gland
which secrete the pancreatic juice.
8. Exocrine Pancreas
It consist of acini,which are of serous type.
The acini are pear-shaped or short tubular groups of
pancreatic cells at the tip of inter-lobular ducts.
The connective tissue is very little between two acini.
Each acinus consists of a group of pyramidal cells
with their apical tips towards the lumen.
The cells rest upon the basal lamina.
Each cell has a big basal spherical nucleus and one
or two nucloeli.
Half of the cell towards the lumen contains numerous
zymogen granules in the cytoplasm.
The basal zone contains endoplasmic reticulum and
elongated mitochondria.
The apical region of the cells shows irregular
microvilli.
9. In the lumen of many acini one or more epithelial
cells, lying in contact
The exocrine pancreas is classified as a
compound tubuloacinous gland. The cells that
synthesize and secrete digestive enzymes are
arranged in grape-like clusters called acini,
very similar to what is seen in salivary glands.
Acini
cells
10. Pancreatic Ducts:- Digestive enzymes from
acinar cells ultimately are delivered into the
duodenum. Secretions from acini flow out of the
pancreas through a tree-like series of ducts. Duct
cells secrete a watery, bicarbonate-rich fluid
which flush the enzymes through the ducts and
play a pivotal role in neutralizing acid within the
small intestine. Pancreatic ducts are classified
into four types which are discussed here
beginning with the terminal branches which
extend into acini.
11. Intercalated ducts receive secretions from acini.
They have flattened cuboidal epithelium that
extends up into the lumen of the acinus to form
what are called centroacinar cells.
Intercalatted ducts
12. Intralobular ducts have a classical cuboidal
epithelium and, as the name implies, are seen
within lobules. They receive secretions from
intercalated ducts.
Intralobular duct
13. Interlobular ducts are found between lobules,
within the connective tissue septae. They vary
considerably in size. The smaller forms have a
cuboidal epithelium, while a columnar epithelium
lines the larger ducts. Intralobular ducts transmit
secretions from intralobular ducts to the major
pancreatic duct.
14. The main pancreatic duct received secretion
from interlobular ducts and penetrates through
the wall of the duodenum. In some species,
including man, the pancreatic duct joins the bile
duct prior to entering the intestine
15. The endocrine portion of the pancreas takes the
form of many small clusters of cells called islets of
Langerhans or, more simply, islets. Humans have
roughly one million islets
In standard histological sections of the pancreas,
islets are seen as relatively pale-staining groups of
cells embedded in a sea of darker-staining
exocrine tissue. The image to the right shows
three islets in the pancreas of a horse.
16. Pancreatic islets house three major cell types,
each of which produces a different endocrine
product:
Alpha cells (A cells) secrete the hormone
glucagon.
Beta cells (B cells) produce insulin and are the
most abundant of the islet cells.
Delta cells (D cells) secrete the hormone
somatostatin, which is also produced by a
number of other endocrine cells in the body
