Histology of Esophagus for 2nd Year by DR SUNDUS

8/2/2019 Histology of Esophagus for 2nd Year by DR SUNDUS

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HISTOLOGY OF

GIT

BY

DR SUNDUS TARIQ


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GIT


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GENERAL STRUCTURE OF THE DIGESTIVE TRACT

The entire tubular gastrointestinal tract hascertain common structural characteristics. It isa hollow tube with a lumen of variable

diameter and a wall made up of four mainlayers:

1. Mucosa,

2. Submucosa,3. Muscularis externa

4. Serosa / Adventitia


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1. MUCOSA

Epithelial lining Lining luminal surface of

organ.

Lamina propria Loose connective tissue rich

in blood vessels, lymphatics,lymphocytes, plasma cellshistiocytes, sometimes alsocontaining glands.

Muscularis mucosae thin layer of longitudinal

smooth muscle

usually separates mucosafrom submucosa.

The mucosa is frequentlycalled a mucous membrane.


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2. SUBMUCOSA

Areolar connective

tissue

Plexuses of blood and

lymph vessels Submucosal plexus of

autonomic nerves

(Meissners plexus).

Glands and lymphoid

tissue.


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Meissners Plexus

Network of ganglia andinterconnecting nervefiber bundles

Parasympatheticpostganglionic motorneurons

Sensory neurons

Interneurons

Innervate muscularismucosae and glands of

GIT.


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3. MUSCULARIS

Smooth muscle cells spirally oriented

divided into two sublayers.

Internal layer, circular.

External layer, longitudinal.

In the connective tissue betweenthe muscle layers are blood andlymph vessels, as well as anotherautonomic myenteric nerveplexus (Auerbachs plexus).

This and the submucosal plexustogether comprise the localenteric nervous system.


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4. SEROSA

Thin layer of loose C.T, rich inblood vessels, lymphatics, andadipose tissue, with a simplesquamous covering epithelium(mesothelium).

In the abdominal cavity, theserosa is continuous with themesenteries and with theperitoneum.

In places where the digestivetract is not suspended in a cavitybut bound to other structures,

such as in the esophagus, theserosa is replaced by a thickadventitia, consisting of C.T.containing vessels and nerves,lacking mesothelium.


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MEDICAL APPLICATION

In certain diseases, such as Hirschsprungdisease (congenital megacolon) or Chagasdisease (Trypanosoma cruzi infection), the

plexuses in the digestive tract are severelyinjured and most of their neurons aredestroyed.

This results in disturbances of digestive tractmotility, with frequent dilatations in someareas.


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MEDICAL APPLICATION

HIRSCHSPRUNG DISEASE CHAGAS DISEASE (ACHLASIA)


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ESOPHAGUS

the esophagus is a

muscular tube whose

function is to transport

food from the mouth tothe stomach.

In general, the

esophagus has the

same major layers asthe rest of the digestive

tract.


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HISTOLOGY OF ESOPHAGUS

1. Mucosa:

It is lined by non-keratinizedstratified squamousepithelium.

lamina propria: looseareolar C.T. with scatteredlymphatic tissue.

In the upper and lower 1/3of esophagus are presentsmall mucus-secreting

esophageal glands. Muscularis mucosae: thick,

longitudinally runningsmooth muscle layer.


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2. Submucosa:

loose areolar C.T

Meissners plexus

Deep submucosal

esophageal glands


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3. muscularis:

In the proximal third ofthe esophagus themuscularis is exclusively

skeletal muscle. The middle third contains

a combination of skeletaland smooth musclefibers.

in the distal third themuscularis contains onlysmooth muscle.


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UPPER ESOPHAGUS


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LOWER ESOPHAGUS


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4. Adventitia (serosa):

the most distal portion ofthe esophagus, in theperitoneal cavity, is

covered by serosa. serosa: adventia +

mesothelium

The rest is enclosed by alayer of loose connective

tissue, the adventitia(fibrosa), which blendsinto the surroundingtissue.


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Histology of Esophagus for 2nd Year by DR SUNDUS

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