Histology of Git and Circulatory System

8/15/2019 Histology of Git and Circulatory System

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Contents

Esophagus

Stomach

Small Intestine

Large Intestine


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Histology of the Digestive System

Basic Histological Layers:1. Mucosa:

a. Epithelium

b. Lamina Propria

c. Muscularis Mucosae2. Submucosa:

Submucosal plexus

“Plexus of Meissner”

3. Muscularis:Myenteric plexus

“Plexus of Auerbach

4. Serosa


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Histology of the Mucosa

Organ EpitheliumMouth Nonkeratinized Stratified Squamous

Pharynx Nonkeratinized Stratified Squamous

Esophagus Nonkeratinized Stratified Squamous

Stomach Simple Columnar

Small Intestine Simple Columnar

Large Intestine Simple Columnar

Anus Nonkeratinized Stratified Squamous


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Histology of the Mucosa

Organ Folds of the epithelium

Esophagus none

Stomach Rugae, gastric pits

Small Intestine Plicae circulares, Villi

Crypts of Lieberkuhn, microvilli

Large Intestine Haustra , Intestinal glands


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Histology of the Submucosa

Organ Specialized structures

Esophagus Submucosal mucous glands

Stomach None

Duodenum Brunner’s glands

Ileum Peyer’s Patches

Large Intestine None


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Histology of the Muscularis

Organ Smooth muscle layers

Esophagus 2, circular and longitudinal

Stomach 3, oblique, circular, andlongitudinal

Small Intestine 2, circular and longitudinal

Large Intestine 2, circular and longitudinal


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Histology of the Serosa

Organ Serosa

Esophagus Adventitia due to the fact that the

esophagus is not in a cavityStomach Visceral Peritoneum

Small Intestine Visceral Peritoneum

Large Intestine Visceral Peritoneum

Anus Adventitia


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Esophagus

Mucosa: Stratified squamousnon - keratinized epithelium

Submucosa: containsMeissner’s plexus andesophageal glands

Muscularis externa:

Upper one-third: skeletalfibres

Middle one-third: mixed

fibresLower one-third: smooth

fibres

Adventitia: loose areolar

connective tissue


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Esophagus


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Esophagus


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Stomach

Stomach is divided intothree histological regionson the basis of nature ofglands:

Cardiac region

Fundic region (fundus &body)

Pyloric region


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Stomach (Cardiac Region)

Mucosa: simple columnar with oval nuclei, mucoussecreting cardiac glands inlamina propria.

Submucosa: connectivetissue.

Muscle layer: innercircular, outer longitudinal.

Serosa: simple squamousepithelium.


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Stomach (Fundic Region)

Mucosa: simple columnar with oval nuclei, presence of

gastric glands in laminapropria.


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Stomach (Fundic Region)

Cells of fundicregion:

Mucous neck cells Parietal (oxyntic) cells

Chief (peptic/zymogen) cells

Enteroendocrine cells Undifferentiated cells


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Cells of fundic region


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Cells of fundic region


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Stomach (Fundic Region) Submucosa: contains blood

vessels, lymphatics andMeissner’s plexus.

Muscularis Externa: an inner

oblique (absent in pylorus),middle circular and outerlongitudinal layer.

Serosa: consist of surface

layer of flattened mesothelialcells resting on a thin layer ofloose connective tissue withblood vessels and lymphatics.


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Stomach (Pyloric Region)

Mucosa: pyloric glands inlamina propria & deepergastric pits extending halfthe thickness of mucosa.

Muscularis Externa: innercircular (thickened to formpyloric sphincter) and outerlongitudinal layer.

Submucosa & Serosa: sameas in fundic part.


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Stomach (Pyloric Region)


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Pyloric Glands


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Gastro-Duodenal Junction


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Small IntestineIt is divided into duodenum, jejunum

and ileum.

Mucosa: characteristic features-

Plicae circularis (valves of Kerkring)

Villi & Microvilli

Goblet cells (few)

Crypts of Lieberkuhn (intestinalglands)

Glands are lined by columnar cells,

goblet cells, Paneth cells &enteroendocrine cells


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Small Intestine


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Small Intestine

Submucosa: containsblood vessels, lymphaticsand Meissner’s plexus.

Muscularis externa: Outer longitudinal andinner circular layers of

smooth muscle. Serosa/Adventitia


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DuodenumPresence of Brunner’s glands

in submucosa


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High power view of

the Duodenal Mucosa


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Jejunum

Villi are tongue shaped.

Absence of Brunner’sglands.


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Ileum

Presence of lymphoidaggregations in laminapropria known as Peyer’s patches.

Villi are short & finger like.


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Large Intestine It consists of: appendix, colon, rectum and anal canal.

Mucosa: Absence of Plicae circulares and villiPresence of Microvilli

Presence of Crypts of Lieberkuhn

Presence of Goblet cells in large number

Submucosa

Muscularis externa:

Inner circular layer - thin compared to small intestine.

Outer longitudinal layer- forms Taenia coli. Adventitia: Appendices epiploicae (peritoneum forms

pouch like processes filled with fat)


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Large Intestine


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Magnified view of a villus


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Large Intestine


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Large intestine


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Vermiform Appendix

A small blind-endingdiverticulum.

Large accumulations oflymphoid tissue in lamina

propria which may extendinto submucosa.

Intestinal villi are usuallyabsent.

Crypts are poorly formed.

Muscularis externa is thin.

Absence of taenia coli.


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Vermiform Appendix


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Rectum

Intestinal glands arestraight, like test tubes.

A continuous coat of

longitudinal muscle ispresent.

Absence of taenia.

Absence of appendices

epiploicae.


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Anal Canal Epithelium: upper part-simple

columnar, middle part-stratifiedsquamous non-keratinized, lowerpart-covered by true skin.

Mucosa has characteristiclongitudinal folds- Anal columns.

Small mucosal folds between theanal columns -Pectinate line.

Crypts disappear below this line. Muscularis externa-circular

muscle forms involuntaryinternal anal sphincter.


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Ano-rectal Junction


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Li


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Liver


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PANCREAS


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GALL BLADDER

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Histology of Git and Circulatory System