Transcript
Histology of gastrointestinal tractHistology of gastrointestinal tractHistology of gastrointestinal tractHistology of gastrointestinal tract
Gastrointestinal tract has four distinct layers Mucosa Mucosa
Epithelium
L i i i f i Lamina propria – supporting function Consist of loose connective tissue (elastic fibers), vessels, nerves,
l d l h id i (i i )glands, lymphoid aggregation (immunity)
Muscularis mucosae – thin smooth muscle layer that is involved in the movement of mucosa
Submucosa Consist of loose connective tissue, large vessels, nerves,Consist of loose connective tissue, large vessels, nerves,
glands, submucosal, submucosus nerve plexus (Meissner´s plexus), and lymphoid aggregation (immunity)gg g
Muscularis propria Muscular wall consist of smooth muscle arranged in two Muscular wall consist of smooth muscle arranged in two
layers, inner circular and outer longitudinal Participate in the peristaltic contraction Participate in the peristaltic contraction Myenteric nerve plexus (Auerbach´s plexus) is located
between these two layersbetween these two layersAdventitia (serosa)
C i f l i i l l Consist of loose connective tissue, large vessels, nerves, adipose tissue covered by the simple squamous epithelium (mesothelium)(mesothelium)
Microscopic preparation Microscopic preparation –– the mucosa of the the mucosa of the tonguetongue
Circumvallate papillae
Stratified squamous epithelium
Taste buds embedded in the epithelium Taste buds embedded in the epithelium
Lamina propria form the body of papilla
Microscopic preparation Microscopic preparation –– the mucosa of the the mucosa of the tonguetonguetonguetongue
Circumvallate papilla Filiform papilla
epithelium
Lamina propria mucosae
Taste buds
Microscopic preparation Microscopic preparation –– the mucosa of the the mucosa of the tonguetongue (taste buds)(taste buds)
Taste bud
Microscopic preparationMicroscopic preparation –– EsophagusEsophagus
Mucosa Stratified squamous epithelium Stratified squamous epithelium
mechanical protection Lamina propria mucosae
l i i l h id i (i i ) loose connective tissue, lymphoid tissue (immunity) Muscularis mucosae
Submucosa
Muscularis propria Inner circular smooth muscle layer Outer longitudinal smooth muscle layer
Ad i i Adventitia
Muscularis propria
EsophagusEsophagusp p
submucosa
mucosa
Microscopic preparationMicroscopic preparation –– EsophagusEsophagus
Epithelium
L h dLymph node
Lamina propria mucosae
Lamina muscularis mucosaemucosae
Submucosa
Microscopic preparationMicroscopic preparation –– EsophagusEsophagus
Circular Longitudinal
Microscopic preparationMicroscopic preparation –– StomachStomach MucosaMucosaMicroscopic preparation Microscopic preparation –– StomachStomach -- MucosaMucosa
Mucosa Simple columnar epithelium enters lamina propria and form the
gastric pits Gastric glands enters these gastric pits
Cell population of epitheliump p p Surface mucous cells – production of protective bicarbonate ions
(against hydrochloric acid)( g y ) Parietal (oxyntic) cells – production hydrochloric acid Zymogenic (peptic) cells – located towards the base of the glandsy g (p p ) g
Pepsin – secreting cells
Neuroendocrine cells
Microscopic preparationMicroscopic preparation –– StomachStomachMicroscopic preparation Microscopic preparation –– StomachStomach
Muscularis mucosae – border between mucosa and submucosaS b i t f l ti ti d Submucosa – consist of loose connective tissue and large vessels
Muscularis propria – consist of three layers of smooth musclesmooth muscle Oblique layer
I i l Inner circular Outer longitudinal
Microscopic preparation Microscopic preparation –– StomachStomachp p pp p p
Mucosa
Gastric foldSubmucosa
Muscularis propria
Gastric pit
Mucosa
Gastric glands
Muscularis mucosaeMuscularis mucosae
Microscopic preparation Microscopic preparation –– SmallSmall intestineintestine --mucosamucosa
Mucosa and submucosa forms circular folds called li i lplicae circulares
Mucosa (epithelium and lamina propria) forms intestinal villiintestinal villi
Plica circularis (Kerckringi) -
submucosa
mucosa jejunum
Plica circularis
Circular
Muscularis propria
layer
p p
Longitudinal layer
Microscopic preparation Microscopic preparation –– Small intestine Small intestine --mucosamucosamucosa mucosa
Simple columnar epithelium covers surface of villi and forms intestinal glands
(Lieberkühn crypts)Cell population of epithelium (glands)
Enterocytes contain microvilli on the apical surface Enterocytes – contain microvilli on the apical surface Participate on the absorption
G bl ll l d Goblet cell – located among enterocytes Production of the protective mucin (against hydrochloric acid)
Paneth cells located at the base of the crypt protectivefunction ((againsagains bacteriabacteria))
Plica circularis (Kerckringi) -
submucosa
mucosa jejunum
Plica circularis
Circular
Muscularis propria
layer
p p
Longitudinal layer
SmallSmall intestineintestine –– mucosamucosa
Intestinal vilus
Intestinal glands(Lieberkühn)
Paneth cells
SmallSmall intestineintestine –– villivilli
Goblet cell
Connective tissue + vesselsConnective tissue + vessels
Enterocyte
PancreasPancreas
Pancreas is mixed exocrine (digestive system) and endocrine
gland.
Endocrine part forms pancreatic islets called islets of Endocrine part forms pancreatic islets called islets of
Langerhans
There are four types of cell including
Alpha cells secrete glucagon Alpha cells – secrete glucagon
Beta cells – secrete insulin
Delta cells – secrete somatostatin
F-cells - secrete pancreatic polypeptide
Blood capillaries surround all these cells
PancreasPancreas
Islets of Langerhans
Intrapankreatic vessel
duct
PancreasPancreas
Islets of Langerhans
Exocrine pancreas
g
Islets of LangerhansLangerhans
Islets of Langerhans
Microscopic preparation Microscopic preparation –– Liver Liver
B l i f li i h i l b lBase structural unit of liver is hepatic lobule It is hexagonaly in shape and is centered on the terminal hepatic
venule (centrilobular venule)venule (centrilobular venule)
Consist of hepatocytes, separated by the vascular channels called i id (bl d f h h i d l i )sinusoids (blood from the hepatic artery and portal vein)
The blood from sinusoids flows into the centrilobular venule → The blood from sinusoids flows into the centrilobular venule → hepatic vein → inferior vena cava
Bile is secreted by hepatocytes → enters bile canaliculi thatempty into small bile ducts
Portal tract (portal triad) located at the angles of the hexagon Portal tract is consist of the vein (branch of hepatic portal vein – nutrition),
the artery (br n h hep ti rter o gen) nd the bile ductthe artery (branch hepatic artery – oxygen) and the bile duct
HepaticHepatic lobulelobule
Portal triad
Vena centralis
PortalPortal triadtriad
bile duct
vein
artery
LiverLiver -- centrilobularcentrilobular venulevenule
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