Gastrointestinal tract II: esophagus, stomach, small intestine, large intestine, appendix 2019/2020
Gastrointestinal tract II: esophagus, stomach, small intestine,
large intestine, appendix2019/2020
HISTOLOGY OF ALIMENTARY CANAL
The histology of the alimentary canal often is discussed in terms of four broad layers: the (1) mucosa, (2) submucosa, (3) muscularis externa, and (4) serosa (or adventitia).
These layers are similar throughout the length of the digestive tract but display regional modifications and specializations.
Alimentary tract. Layer contents are generalized.
Esophagus
“Atlas of Descriptive Histology” Michael H. Ross, Wojciech Pawlina, Todd A. Barnash. 2009
Mucosal and submucosal glands are found in the esophagus.
Slide no. 34
Slide no. 34 Esophagus
Epithelium
THE STOMACH has 4 gross anatomical regions, but only 3 histological regions:(1) the body (corpus) and fundus which are similar histologically(2) the cardia(3) the pylorus
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Fundus/Body Pylorus
Body region including fundus:
➢ The pit : gland ratio is 1:4, that is the pits are short, but the glands are 4 times longer.
➢ The pits are lined by surface mucous cells and the glands are called gastric glands (fundicglands).
➢ The gastric glands are simple tubular glands lined by a simple columnar epithelium
➢ Unlike the cardiac and pyloric glands which are highly coiled, these are relatively straight.
Stomach fundus
Slide no. 35
5 major cell types:
(1) mucous neck cells
(2) chief cells (peptic cells)
(3) parietal cells (oxynticcells)
(4) stem cells
(5) gastroenteroendocrinecells (calledenterochromaffin cellsbecause of their stainingaffinity for chromicacid salts)
Gastric gland proper
Gastric gland
Fundic (or oxyntic) glands: oxyntic (or parietal) and chief cells
Slide no. 35
Parietal cells
(acidophilic)
Chief cells
(basophilic)
Pyloric region:
➢ The pits are lined by the surface mucous cells, but the pits
are very long, with a pit : gland ratio of 2 or 3:1.
➢ The short glands are called pyloric mucous glands, and
they are also divided into an isthmus and gland proper
that is mucous and similar to the cardiac glands in having
round nuclei. Mucosa
Muscularis mucosae
Slide 36
Duodenum
Slide no. 37
Mucosa
Submucosa with Brunner’s glands
Muscularis externa
Small intestine
Muscularis ex.
Serosa
Submucosa
Mucosa
Serosa
Muscularis ex. – 2 layers
Slide no. 38
Mucosa:
villi +
crypts
Small intestine – intestinal villi
Intestinal villi:
simple columnar epithelium
with goblet cells +
lamina propriaSlide no. 38
Magnification 10x
Magnification 4x
Small intestine – crypts & Paneth’s cells
Paneth cells
Paneth cells
Large intestine
Mucosa Submucosa
Muscularis
mucosae
Mucosa
Slide no. 39
The large number of goblet cells which characterize crypt epithelium
SubmucosaC
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Auerbach’s myenteric plexuses
Circular layer
(longitudinal
sections)
Longitudinal
layer (cross
sections)
Myenteric
plexuses
Slide no. 38/39
Lymphatic nodules are a standard feature of the appendix.
AppendixSlide no. 79