1. HISTOLOGY Gastrointestinal & Nutrition Block GNT 223
Histology of the Esophagus and Stomach By
Dr. Einas Yousef
2018/2019

2. Objectives
By the end of this lecture, the student should be able to discuss the microscopic structure, in correlation with the function, of the following organs:
Esophagus.
Stomach.

3. Introduction
Digestive system is consists of digestive tract and its associated gland.

4. Histology of the Digestive Tract
The wall of the gastrointestinal tube is formed of four layers. From the lumen outwards these layers are:
1. Mucosa (Epithelium, Lamina propria, Muscularis mucosa)
2. Submucosa
3. Muscularis externa (Musculosa)
4. Serosa or adventitia

5. Histology of the Digestive Tract (LS)
L.S= longitudinal section

6. Histology of the Digestive Tract (TS)
T.S.= Transverse section

7. 1- Mucosa A- Epithelium: B- Lamina propria (Corium):
The type of epithelium varies in different type of GIT depending on the function.
Function for protection (esophagus), Secretion (stomach), Absorption of nutrients (intestine).
B- Lamina propria (Corium):
Loose connective tissue with nourishing and absorbing capillaries.
It contains most of mucosa-associated lymphoid tissue
C- Muscularis mucosae
Thin layer of muscle arranged as inner circular and outer longitudinal.
Produce movements of the mucosa.

8. 2- Submucosa
Loose areolar connective tissue containing blood and lymphatic vessels
Submucosal nerves plexus “Meissner Plexus”.
Contain Glands in some parts.
Contain many elastic fibers so gut can regain shape after food passes

9. 3- Muscularis Externa
Two layers of involuntary smooth muscle that arranged as:
A) Inner circular layer (circumferential): in some places forms sphincters (act as valves).
B) Outer longitudinal layer: shortens gut
In between these two layers, there is Myenteric nerve plexus (Auerbach’s Plexus) , blood and lymph vessels
These muscles responsible for peristalsis and segmentation of the digestive tract.

10. 4- Adventitia or Serosa Adventitia Serosa
Certain segments of the GIT are not enveloped by peritoneum.
In those segments, the outermost layer is loose connective tissue (Adventitia) containing blood vessels, lymphatics & nerve fibers.
Adventitia connects the digestive tract to its surroundings.
Serosa
It is the adventitia that is covered by peritoneum.
Thin layer of loose connective tissue covered with simple squamous epithelium (mesothelium)

11. Esophagus
Esophagus is a muscular tube through which food is carried from the pharynx to the stomach.
Descends through thorax and enter the abdomen through the esophageal opening of diaphragm
Esophagus has to be protective, as it is open to the outside. The esophagus also has to accommodate a wide variety of food and drink (hot, cold, spicy etc).
Esophagus

12. Histology of Esophagus
Mucosa:
Epithelium: Non-keratinized stratified squamous.
Lamina Propria (Corium)
Muscularis Mucosae: two thin layers, inner circular (IC) and outer longitudinal (OL).
Submucosa: Loose CT, Plexus of Meissner, Mucous esophageal glands
Muscularis externa (Musculosa): 2 layers; inner circular, outer longitudinal.
Upper 1/3: striated (skeletal) muscle.
Middle 1/3: mixed skeletal and smooth muscles.
Lower 1/3: only smooth muscles.
Serosa or adventitia: All esophagus is covered by adventitia except the intraabdominal part of the esophagus which has a serosal coat.
Skeletal muscle of the esophagus is involuntary controlled by the autonomic nervous system.

13. Histology of Esophagus
Mucosa
Muscularis externa IC OL
Submucosa
Diagram of esophagus
Section of esophagus

14. Stomach
Anatomically, stomach is divided into four regions: Cardiac region, Fundus, Body and Pyloric region.
Histologically, three regions only are described based on the nature of the glands of the lamina propria: Cardiac region, Fundic region (Fundus and Body) and Pyloric region.
Fundic region
Cardiac region
Pyloric region

15. Histology of Stomach
The inner surface of the stomach is thrown into folds called rugae that include both mucosa and submucosa.
Mucosa: Thick mucous membrane, the surface is characterized by invaginations of the lining epith. into the lamina propria forming gastric pits
Epithelium: Simple columnar epithelium
Lamina Propria: contains gastric glands
Muscularis Mucosae: sometimes 3 layers.

16. Histology of Stomach Submucosa: no gland except in pyloric region.
Muscularis externa (Musculosa): 3 layers of smooth muscle, inner oblique, middle circular and outer longitudinal.
In pylorus, the circular muscle layer is thickened to form the pyloric sphincter.
Serosa: loose CT covered with peritoneum.
Gastric pit
Gastric gland
5/2/2019

17. Gastric glands
They are located in the lamina propria of the mucosa of the stomach.
Their opening on the surface of the stomach called gastric pit which is shallow in the cardiac region and deep in the pyloric region.
Gastric glands possess:
Isthmus: upper part of the gland connect the gland to the bottom of the gastric pit.
Neck: is the middle part.
Base: is the deep part.
Parts of gastric glands
Gland

18. Cells of the gastric glands
1- Surface mucous cells:
Simple columnar cells with basal oval nuclei.
Site: In the isthmus and are continuous with the lining epithelium of the gastric pits.
Function: They secret neutral mucous which protects against HCL in gastric lumen and lubricate the surface.
2- Mucous neck cells
Low columnar cells with basal flattened nuclei. They have numerous mitochondria, RER, Golgi apparatus, many apical mucous secretory granules.
Site: in the neck of the glands.
Function: They secret acid mucous & lysosome enzyme.
5/2/2019

19. Cells of the gastric glands
3- Parietal (Oxyntic) cells:
Rounded or triangular cells with acidophilic cytoplasm and central rounded nucleus.
They do not reach the lumen of the gland
They contain few RER and ribosomes, numerous mitochondria, well developed SER, many intracellular canaliculi with numerous long microvilli on surface.
Site: Mainly in the isthmus and neck regions of the glands.
Function: Secretion of HCL & intrinsic factor (Vit. B12 absorption).
Parietal=جدارى

20. Cells of the gastric glands
4- Chief (zymogenic or peptic) cells
They are the most numerous cells.
Pyramidal cells with basal rounded nuclei.
They have well developed RER, supranuclear Golgi apparatus and apical secretory zymogenic granules.
Site: Mainly in the base of the glands.
Function: production of the main gastric enzymes: pepsinogen, renin and gastric lipase.
N.B. Zymogen is a proenzyme which is an inactive precursor of an enzyme which require biochemical changes to become active.

21. Cells of the gastric glands
5- Enteroendocrine (Argentaffin, APUD) cells
Pyramidal cells with darkly stained nuclei.
Site: Mainly in the base of the glands and also in the small and large intestine.
Function: Secretion gastrointestinal hormones such as gastrin, serotonin, endorphin in blood (Endocrine).
6- Regenerative (stem) cells
They are small cells with oval basal nuclei.
They are located mostly in the neck, isthmus and gastric pits.
They are capable of replacing all cells in the gastric gland.
APUD= amine precursor uptake and decarboxylation
5/2/2019

22. Gastric glands Cardiac gland Fundic gland Pyloric gland Other name
Zymogenic glands
Mucoparietal glands
Gastric pits
Medium sized pits
Short and narrow (Smallest gastric pits)
Deep and wide
Type of the gland
Short, Simple, branched, coiled tubular glands
Simple, branched, straight tubular glands
Simple, branched, coiled tubular glands
cells
Possess all types of cells except chief cells
Surface mucous cells.
Mucus neck cells. Undifferentiated stem cells.
Chief cells, oxyntic cells
APUD cells

23. Functions of the Stomach
It is an efficient mixer that transforms the ingested food into a viscous mass called chyme.
HCL secretion which dissolves many of the foods we eat, helps the immune system to fight infections.
Secretion of mucus which protects the stomach wall from HCL.
Secretion of pepsin, renin and lipase the begin the digestion of food.
Secretion of enzyme lysosome which is bactericidal .
Secretion of some hormones (Mixed endocrine and exocrine gland).

24. References
Junqueira C., Carneiro J. (2005). Basic Histology, Text & Atlas, 11th ed.
Gartner LP (2016). Color Textbook of Histology. 4th ed. Philadelphia: Saunders WB.
Young B, O' Dowd G, Woodford P (2013). Wheater‟s Functional Histology. 6th ed. London: Churchill Livingstone.

25. Any Question