HISTOLOGY OF GIT- 2

GIT-2
DR.DEEPAK N.KHEDEKAR
DEPARTMENT OF
ANATOMY
LTMMC
DEC- 2016

12/14/2016 DR.DEEPAK N.KHEDEKAR/LTMMC/2016

• Cardiac region (cardia)-
part near the esophageal
orifice, contains the
cardiac glands
• Pyloric region (pylorus)-
part proximal to the
pyloric sphincter, which
contains the pyloric
glands
• Fundic region (fundus)-
largest part , which is
situated between the
cardia and pylorus and
contains the fundic or
gastric glands
STOMACH-Divided histologically
into three regions

GASTRIC MUCOSA
Rugae-
• Longitudinal
submucosal folds
Gastric pits, or
foveolae-
• Numerous in the
mucosal surface.
• Gastric glands open
into the bottom of the
gastric pits.

GASTRIC MUCOSA
• Lining of the stomach-simple columnar E.
• Columnar cells are -Surface mucous cells
Surface mucous cells :
• Possesses a large, apical cup of mucinogen granules
• Occupies most of the volume of the cell.
• Appears empty in routine (H&E) sections because
the mucinogen is lost in fixation and dehydration.
• When the mucinogen is preserved, the granules
stain intensely with toluidine blue and with the PAS

ESOPHAGOGASTRIC JUNCTION,
• Stratified squamous
epithelium of the esophagus
ends abruptly, and the simple
columnar epithelium of the
stomach mucosa begins.
• Surface of the stomach show
numerous and deep
depressions
• Glands in the vicinity of the
esophagus , the cardiac
glands
• Extend from the bottom of
these pits.
 Fundic (gastric):
• Glands arise at the base of
the gastric pits and are
evident in the remaining part
of the mucosa.
• Thick muscularis externa. .

RUGAE
• BV- Blood vessels
• M- Mamillated areas
• ME- Muscularis
externa
• Muc- Mucosa
• SM- Smooth muscle
cells
• SubM- Submucosa
• Arrows three
differently stained
regions of fundic
mucosa;

FUNDIC
MUCOSA
• Alcian Blue/PAS.
• One of the gastric pits
& Associated fundic
gland
• Nucleus and Golgi
apparatus are located
below the mucous
cup.
• Basal part of the cell
contains small
amounts of rER that
impart a light
basophilia to the
cytoplasm.

FUNDIC GLANDS
• A- Adipocytes,BV- blood vessels
• CC- Chief cells,GC- ganglion cells
• ME- Muscularis externa
• MM- Muscularis mucosae
• MNC- Mucous neck cells
• MP- Meissner’s plexus
• N- Neck of fundic glands
• PC- Parietal cells
• SMC- Surface mucous cells
• SubM- Submucosa
• Arrows- Argentaffin cells
• Arrowheads- nuclei of satellite
cells

FUNDIC GLANDS (GASTRIC GLANDS )
• Present throughout the entire gastric mucosa
• Simple, branched, tubular glands
• Extend from the bottom of the gastric pits to the
muscularis mucosae.
• Has a narrow, long neck segment and a shorter and
wider base or fundic segment.

ISTHMUS OF THE FUNDIC GLAND - SITE OF
STEM CELLS
• Short segment -Located between the gastric
pit and the gland
• Cells destined to become mucous surface cells
migrate upward in the gastric pits to surface.
• Other cells migrate downward, maintaining
the population of the fundic gland epithelium.

FUNDIC GLANDS
Composed of four functionally different
cell types…
• Mucous neck cells
• Chief cells
• Parietal cells, also called oxyntic cells
• Entero-endocrine cells
• Undifferentiated adult stem cells

1.MUCOUS NECK CELLS
• Located in the neck region of the fundic gland.
• Much shorter than the surface mucous cell and
• Contains less mucinogen in the apical cytoplasm.
• Do not exhibit a prominent mucous cup.
• Nucleus tends to be spherical compared with the
more prominent, elongated nucleus of the surface
mucous cell.
• Parietal cells are interspersed between these cells

2.CHIEF CELLS
• Located in the deeper part of the fundic glands.
• Typical protein-secreting.
• Basal cytoplasm- basophilic due the abundant
rER ,
• Apical cytoplasm- eosinophilic due to presence
of the secretory vesicles, zymogen granules
• Zymogen granules contain enzyme precursors.
• Basophilia, in particular, allows easy
identification of these cells in H&E sections

3.PARIETAL CELLS (0XYNTIC CELLS)
• Found in the neck glands, among the mucous
neck cells, and in the deeper part.
• More in no. in the upper & middle part.
• Large cells, binucleate, and appear triangular in
sections, with the apex directed toward the
lumen of the gland and the resting on the basal
lamina.
• Nucleus-spherical
• Cytoplasm- stains with eosin and other acidic
dyes.

CHIEF CELL VS PARIETAL CELL

Parietal cells-TEM STUDY
• Show intracellular canalicular system
• Communicates with the lumen of the gland.
• Numerous microvilli project from the surface of the
canaliculi, and an elaborate tubulovesicular membrane
system is present in the cytoplasm adjacent to the
canaliculi.
• In an active cell, the number of microvilli in the
canaliculi increases, and the tubulovesicular system is
reduced significantly or disappears.
• Membranes of the tubulo-vesicular system serve as a
reservoir of plasma membrane containing active
proton pumps.

TEM

4.ENTERO-ENDOCRINE CELLS
• Found in fundic gland, more
prevalent in the Base
• 2 types can be distinguished
Closed” cells-
• Small cells ,rest on the basal
lamina , do not always reach the
lumen;
0pen” cells-
• Have a thin cytoplasmic extension
bearing microvilli that are
exposed to the gland lumen

CARDIAC GLANDS OF THE GASTRIC MUCOSA
• Composed of mucus-secreting cells, with occasional
interspersed entero-endocrine cells.
• Glands are tubular, tortuous, and branched.
• Location- narrow region of the stomach (cardia) that
surrounds the esophageal orifice.
• Secretion, in combination with that of the esophageal
cardiac glands, contributes to the gastric juice and
helps protect the esophageal epithelium against gastric
reflux.
• Appearance –Similar to esophageal cardiac glands.

CARDIAC GLANDS
• Tubular, tortuous, and
occasionally branched.
• Composed mainly of mucus-
secreting cells
• Similar in appearance to the
cells of the esophageal
glands.
• Mucous secretion reaches
the lumen of the gastric pit
via a short duct segment
containing columnar cells.

FUNDO-CARDIAC
JUNCTION, STOMACH,
H&E.
• CG- cardiac glands
• FG- fundic glands
• L- lumen
• LN- lymphatic nodule
• MM- muscularis
mucosae
• P- gastric pits
• PC- parietal cells

FUNDO-CARDIAC JUNCTION, STOMACH,
HUMAN, H&E.
CG- cardiac glands FG- fundic glands L- lumen ,LN- lymphatic nodule
MM- muscularis mucosae ,P- gastric pits PC- parietal cells ,SM- smooth
muscle cells12/14/2016 DR.DEEPAK N.KHEDEKAR/LTMMC/2016

PYLORIC GLANDS
• Branched, coiled, tubular gland.
• Location-Pyloric antrum
• Lumen- wide
• Appearance- cells similar to the surface mucous
cells (viscous secretion)
• Enteroendocrine cells interspersed within the gland
epithelium along with occasional parietal cells.
• Empty secretion into deep gastric pits
• Gastric pits - Half the thickness of the mucosa.
• Help protect pyloric mucosa.

PYLORIC GLANDS
•Relatively straight but
are slightly coiled near
the muscularis mucosae.
•Lumen is relatively wide,
•Secretory cells similar in
appearance to the
surface mucous cells.
•Restricted to the
mucosa and empty into
the gastric pits.

LAMINA PROPRIA OF THE STOMACH
• Relatively scant and restricted to the spaces
surrounding the gastric pits and glands.
• Stroma - composed of reticular fibers with fibroblasts
and smooth muscle cells.
• Other components- lymphocytes, plasma cells,
macrophages, and some eosinophils.
• lymphatic nodules are also present, intruding into
MM.
GASTRIC SUBMUCOSA
• Composed of a dense connective tissue.
• Contain adipose tissue,blood,nerve fibers and ganglion
cells that compose the submucosal (Meissner’s)
plexus.

STOMACH -SUBMUCOSA
A- adipocytes
BV- blood vessels
CC- chief cells
GC- ganglion cells
ME, muscularis externa
MM- muscularis mucosae
MNC- mucous neck cells
MP- Meissner’s plexus
N- neck of fundic glands
PC- parietal cells
SMC- surface mucous cells
SubM- submucosa
arrows, argentaffin cells
arrowheads, nuclei of satellite cells

GASTRIC MUSCULARIS EXTERNA
• Outer longitudinal layer, a middle circular layer,
and an inner oblique layer, Randomly oriented.
• longitudinal layer is absent from much of the
anterior and posterior stomach surfaces
• Circular layer is poorly developed in the peri-
esophageal region
• Myenteric (Auerbach’s) PLX- Ganglion cells and
bundles of unmyelinated nerve fibers are
present betwn the muscle layers.
SEROSA

SMALL INTESTINE
• Longest component of the GIT , measuring over 6 m,
and is divided into three anatomic portions:
Duodenum (25 cm long) -first, shortest, and widest
part of the small intestine. It begins at the pylorus of
the stomach and ends at the duodenojejunal jn
Jejunum (2.5 m long)- begins at the duodenojejunal
junction and constitutes the upper two fifths of the
small intestine
 Ileum (3.5 m long) is a continuation of the jejunum
and constitutes the lower three fifths. It ends at the
ileocecal junction.

SEGMENT OF JEJUNUM
• Circular folds ( plicae
circulares) appear as a series
of transversely oriented ridges
• Extend partially around the
lumen.
• Some of the circular folds
appear to end (or begin) at
various sites along the luminal
surface (arrows).
• Entire mucosa has a velvety
appearance because of the
presence of villi.

A.MUCOSA
Absorptive surface area is amplified by.
PLICAE CIRCULARES,
VILLI
MICROVILLI

1.Plicae circulares (circular folds), valves of
Kerckring
• Permanent transverse folds, contain a core of
submucosa.
• Each circular fold is circularly arranged and
extends about one half to two thirds of the way
around the circumference of the lumen.
• Begin to appear about 5 to 6 cm beyond the
pylorus.
• Most numerous in the distal part of the
duodenum and the beginning of the jejunum and
become reduced in size and frequency in the
middle of the ileum.

2.VILLI
• Unique, fingerlike and leaflike projections, Extend from
the mucosal surface for 0.5 to 1.5 mm into the lumen
• Cover the surface , giving it a velvety appearance.
• Consist of a core of loose CT covered by a Simple
columnar E.
• Core of the villus - an extension of the lamina propria ,
which contains fibroblasts, smooth muscle cells,
lymphocytes, plasma cells, eosinophils , macrophages,
and a network of fenestrated blood capillaries and also
lymphatic capillary, the lacteal.

2.VILLI

3.MICROVILLI-ABSORPTIVE
CELL-ENTEROCYTE
• Provide the major
amplification of the
luminal surface.
• Each cell possesses
several thousand
closely packed
microvilli .
• Visible in the light
microscope and
give the apical
region of the cell a
striated
appearance, the so-
called striated
border.

A.1.LINING EPITHELIUM
• Simple Columnar Epithelium
INTESTINAL GLANDS
(CRYPTS OF LIEBERKÜHN)
• Simple tubular structures
• Extend from the MM through the thickness of the
lamina propria
• Open onto the luminal surface of the intestine at
the base of the villi
• Lined by simple columnar epithelium that is
continuous with the lining epithelium of the villi.

A.2.LAMINA PROPRIA
• Surrounds the intestinal glands
• Contains numerous cells of the immune system
(lymphocytes, plasma cells, mast cells,
macrophages, and eosinophils), particularly in the
villi.
• Contains numerous nodules of lymphatic tissue
that represent a major component of the GALT.
• Nodules are large and numerous in the ileum,
where they are located on the side of the intestine
opposite the mesenteric attachment .
• Nodular aggregations are known as aggregated
nodules or Peyer’s patches.

A.3.MUSCULARIS MUCOSAE
• Consists of two thin layers of smooth muscle
cells, an inner circular and an outer longitudinal
layer.
• Strands of smooth muscle cells extend from the
muscularis mucosae into the lamina Propria of
the villi.

CELLS IN INTESTINAL MUCOSAL
EPITHELIUM.
They include the following:
Enterocytes- whose primary function is absorption
Goblet cells- unicellular mucin-secreting glands
Paneth cells- whose primary function is to maintain
mucosal innate immunity by secreting antimicrobial
Substances
Enteroendocrine cells- which produce various
paracrine and endocrine hormones
M cells (microfold cells)- modified enterocytes that
cover enlarged lymphatic nodules in the lamina
propria

ENTEROCYTES
• Tall columnar cells with a basal Nucleus
• Microvilli -increase the apical surface area as
much as 600 times;
• form a striated border on the luminal surface
• Lateral cell surface exhibits elaborate,
flattened cytoplasmic processes (plicae) that
interdigitate with those of adjacent cells .
• Folds increase the lateral surface area of the
cell, thus increasing the amount of plasma
membrane containing transport enzymes

ENTEROCYTE

GOBLET CELLS
• Unicellular glands, produce mucus ,are interspersed
among the other cells of the intestinal epithelium.
• Increase in number from the duodenum to the
terminal part of the ileum.
• As water-soluble mucinogen is lost during
preparation of routine H&E sections, the part of the
cell that contains mucinogen granules appears empty.
• Examination with the TEM- reveals a large
accumulation of mucinogen granules in the apical
cytoplasm that distends the apex of the cell and
distorts the shape of neighboring cells

GOBLET CELL• Basal portion of the cell
contains the nucleus, rER,
and mitochondria.
• Just apical to the nucleus are
extensive profiles of Golgi
apparatus. As the mucous
product accumulates in the
Golgi cisternae, they become
enlarged.
• Mucous cup -Large
mucinogen granules fill most
of the apical portion of the
cell.

PANETH CELLS
• Found in the bases of the intestinal glands
• Occasionally found in the normal colon in small
numbers; No. increases in pathologic conditions.
• Have a basophilic basal cytoplasm, a supranuclear
Golgi apparatus, and large, Intensely acidophilic,
refractile apical secretory vesicles.
• Vesicles allow their easy identification
Paneth cells play a role in regulation of normal
bacterial flora of the small intestine.

BASE OF INTESTINAL
(JEJUNAL) GLANDS IN AN
H&E
Paneth cells-
 located in the base of the
intestinal glands , readily
 intensive eosin staining of
vesicles.
LP- contains of plasma cells,
lymphocytes, and other CT
cells.
Inset. High magnification –
 Basophilia in the basal
portion of the cell and
 Eosinophilic, refractile
secretory vesicles in the
apical portion of the cell.

M CELLS
• Cells that overlie Peyer’s patches and other large
lymphatic nodules;
• Differ significantly from the surrounding intestinal
epithelial cells .
• Have microfolds rather than microvilli on their
apical surface, and they take up Microorganisms
and macromolecules from the lumen in endocytotic
vesicles.
M cells convey microorganisms and other
macromolecules from the intestinal lumen to
Peyer’s patches.

ENTERO-ENDOCRINE CELLS
• Resemble those that reside in the stomach .
• “Closed cells”- concentrated in the lower
portion of the intestinal gland,whereas the
• “Open cells” -found at all levels of each villus.
• Activation of taste receptors -found on the
apical cell membrane of “open cells” activates G
protein–signaling cascade, resulting in releasing
of peptides that regulate a variety of
gastrointestinal functions.

INTERMEDIATE CELLS
• Constitute most of the cells found within the intestinal
stem cell niche
• Located in the lower half of the intestinal gland.
• Constitute the amplifying compartment of the cells
• Capable of cell division and usually undergo one or
two divisions before they become committed to
differentiation into either absorptive or goblet cells.
• Have short, irregular microvilli with long core
filaments extending deep into the apical cytoplasm
and numerous macular (desmosomal) junctions with
adjacent cells.

Intermediate cells
(Stem cells)
Goblet cells
(Increase in
secretory granules)
Absorptive cells
(Loss of secretory
granules)

GALT
• LP of the GI tract is heavily populated with
elements of the immune system;
• Approximately one-fourth of the mucosa consists
of a loosely organized layer of lymphatic nodules,
lymphocytes, macrophages, plasma cells, and
eosinophils in the lamina propria.
• Lymphocytes are also located between epithelial
cells.
GALT serves as an immunologic barrier throughout
the length of the gastrointestinal tract.

SUBMUCOSA
• Consists of a dense CT and localized sites that
contain aggregates of adipose cells.
• Distinguishing characteristic of the duodenum is
the presence of submucosal glands i.e Brunner’s
glands (Branched, tubular,have secretory cells with
characteristics of both zymogen secreting and
mucus-secreting cells.
Muscularis externa
• Consists of an inner circular and an outer
longitudinal smooth muscle cells with Myenteric
plexus (Auerbach’s plexus)

1.DUODENUM-
BRUNNERS GLAND
• Dashed line -boundary
between the villi and the
typical intestinal glands
(crypts of Lieberkühn).
extending to the MM.
• Submucosa-contains
Brunner’s glands.
• These are branched tubular
glands whose secretory
component consists of
columnar cells.
• Duct of the Brunner’s
gland -opens into the
lumen of the intestinal
gland (arrow). 120.12/14/2016 DR.DEEPAK N.KHEDEKAR/LTMMC/2016

1.Duodenum

2.Jejunum.
PC- plicae circulares, Muc- mucosa, V- villi ,
ME- muscularis externa, SubM- submucosa

2.Jejunum.• EC- endothelial cell
• GC- goblet cell
• GI- intestinal glands
• L- lacteal
• LP- lamina propria
• Ly- lymphocytes
• M- smooth muscle
• MM- muscularis m.
• S- serosa
• SB- striated border
• Arrow- basal processes
of enterocytes
• asterisks, basal-lateral
intercellular spaces
• dashed line-boundary
between villi and
intestinal glands

• LN, lymphatic nodules ME, muscularis externa
• Mucosae SM, submucosa V, villi
ILEUM

ILEUM Gl- intestinal glands, MM- Muscularis Mucosae
MM??- presumptive location of muscularis ,Asterisks- leaf
like villus12/14/2016 DR.DEEPAK N.KHEDEKAR/LTMMC/2016

LARGE INTESTINE

COLON
BV- blood vessels , ME- muscularis externa ME(c), circular layer of
muscularis externa ME(l)- longitudinal layer of muscularis externa Muc,
mucosa S, serosa SubM, submucosa TC, tenia

Mucosa
• Smooth surface, Neither plicae circulares nor villi are
present.
• Contains numerous straight tubular intestinal glands
• Glands extend through the full thickness of the mucosa
• Glands consist of simple columnar epithelium, as does
the intestinal surface from which they invaginate.
• O/E of luminal surface at the microscopic level reveals
the openings of the glands, which are arranged in an
orderly pattern
• Morphology of absorptive cells is essentially identical
to that of the Enterocytes of the small intestine

The mucosal epithelium of the large intestine
contains the same cell types as the small
intestine except Paneth cells, which are
normally absent in humans
• Columnar absorptive cells predominate (4:1)
over goblet cells

COLON
• A- Adipose tissue, GI- intestinal glands , LP-lamina propria ,
Arrows- opening of intestinal glands

LAMINA PROPRIA
• 1.Collagen table- thick layer of collagen and
proteoglycans lies between the basal lamina of
the epithelium and that of the fenestrated
absorptive venous capillaries.
• 5 m thick in the normal human colon.
• participates in regulation of water and electrolyte
• transport from the intercellular compartment of
the epithelium to the vascular compartment

LAMINA PROPRIA
Pericryptal fibroblast sheath-
• constitutes a well developed fibroblast
population of regularly replicating cells.
• Divide immediately beneath the base of the
intestinal gland, adjacent to the stem cells.
• fibroblasts then differentiate and migrate upward
in parallel and synchrony with the epithelial cells.
 GALT
 LYMPHATIC VESSELS

COLON
• AC- absorptive cells ,GC- goblet cells ,M-mitotic figures, MM-
muscularis m., Arrowheads- smooth muscle cells showing rounded
nuclei coli ,Asterisks- lumen of intestinal glands ,

MUSCULARIS EXTERNA
• Outer layer, condensed into prominent
longitudinal bands of muscle, called teniae coli,
• Inner, circular layer of muscle at irregular
intervals along the length and circumference of
the colon.
SUBMUCOSA AND SEROSA

VERMIFORM APPENDIX

vermiform appendix
• Displays the same four layers as those of the large
intestine
• Its diameter is smaller.
• Typically, lymphatic nodules are seen within the entire
mucosa and usually extend into the submucosa.
• Distinct germinal centers within the lymphatic nodules.
• Muscularis externa is composed of a relatively thick
circular layer and a much thinner outer longitudinal layer.
• Covered by a serosa that is continuous with the
mesentery of the appendix

Cl- gland, L- lumen , LN- lymphatic nodule, ME-
muscularis externa, Muc- mucosa S- serosa, Subm-
submucosa12/14/2016 DR.DEEPAK N.KHEDEKAR/LTMMC/2016

BV- blood vessel ,Cap- cap of lymphatic nodule GC-
germinal center

VERMIFORM APPENDIX
ARROWS- MUSCULARIS MUCOSAE AT BASE OF
GLANDS

THE END

HISTOLOGY OF GIT- 2

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