Lab 19 Esophagus and Stomache: 1) Index 2) Introduction 3) Things to Identify 4) Upper Esophagus 5) Middle Esophagus 6) Lower Esophagus 7) Cardiac Stomach 8) Fundic Stomach 9) Pyloric Stomach 10) Stomach-Duodenal Junction 11) Comparison of Structures 12) Practical

 

Upper Esophagus

 

# 106 - Esophagus, upper, monkey, h-e, 1.5mm, c.s.

# 213 - Esophagus, rabbit, h-e, 1.5mm, c.s.

 

The mucosal surface of the esophagus is covered by an extremely thick stratified squamous epithelium. Notice how papillated this epithelium is. Is this surface keratinized in humans?

The longitudinally arranged muscularis mucosae begins near the cricoid cartilage and is thickest near the stomach. It is prominent in most sections of the esophagus. Is smooth or striated muscle found in the muscularis mucosae?

The submucosa of the esophagus contains thick collagen and coarse elastic fibers in an irregular array as well as the adipose tissue and the mucus - producing esophageal glands proper. These submucosal esophageal glands are to be differentiated from the mucus - producing esophageal cardiac glands (located in the lamina propria of the mucosa). The latter has a very limited distribution in the esophagus (mostly in the region near the stomach).

Are submucosal blood vessels abundant?

One can determine the level of the esophagus from which the specimen was taken based on the type of muscle found in the muscularis externa layer seen in a particular section, The esophageal musculature (muscularis externa) is striated in the upper third, mixed striated and smooth in the mid-section, and smooth muscle in the lower third. It is two-layered (an inner circular layer separated from the outer longitudinal layer by a thin connective tissue band. In the lower parts of the intestine, the myenteric plexus (Auerbach's plexus) helps to coordinate smooth muscle activity . Fibroelastic tissue characterizes the adventitia. allowing it to distend upon swallowing. You may see neurovascular bundles running through this adventitia.

REFERENCES: Gartner, pp. 280-281Ross, p. 443, 474 - 475 DiFiore, p. 175 - 179, Fig. 12-1 - 12.4 Wheater, p. 250 - 251, Fig. 14.3b - 14.4

 

This is a low power image of the Esophagus. In this view you can see the 4 basic layers found in the entire G.I. tract. The green arrow is outlining the inner most layer called the Mucosa. It consists of an epithelium (red arrow) which is stratified squamous non-keratinized epithelium. The next part of the mucosa is the lamina propria (black arrow) which is loose connective tissue, and a Muscualris Mucosa (blue arrow) which is a strap of smooth muscle. The next layer moving outward from the lumen is the Submucosa, indicated by the yellow arrows and is composed of collagen and elastic fibers, just below the muscularis mucosa. The third layer is the Muscularis Externa (white arrows) made up of an internal circular layer and outer longitudinal layer of smooth muscle. Beyond the externa, is the final layer called the Adventitia indicated by the brown arrows.

Green arrow - Mucosa

Red arrow - Epithelium

Black arrow - Lamina propria

Blue arrow - Muscularis Mucosa

Yellow arrow - SubMucosa

White arrow - Muscularis Externa

Brown arrow - Adventitia

This is another image of the esophagus, however, this is taken from the upper part of it. You have your Mucosa, indicated by the blue arrows, the Submucosa, indicated by the yellow arrows, and the Muscularis Externa, indicated by the red arrow. In the upper part of the espophagus, a majority of the muscularis externa is made up of Voluntary Skeletal Muscle. As you go down the esophagus you gradually lose the skeletal muscle for smooth muscle. The green arrows are pointing to the Submucosal Esophageal Glands. These are one of two of the only type of glands found in the submucosa through out the entire GI tract. So seeing these is a good help to know that you are in one of two places, one of them being the esophagus.

Blue arrow - Mucosa

Yellow arrow - Submucosa

Red arrow - Muscularis Externa (Skeletal Muscle)

Green arrow - Submucosal Esophogeal Glands

 

This is a close up of the epithelium of the esophagus which is a Stratified Squamous Non-keratinized epithelium, indicated by the yellow lines. Notice the presence of nuclei in the top layer of cells, (green arrows).

 

Green arrows - Nuclei in Top layer

Yellow lines - Stratified Squamous Non-Keratinized

 

 

 

Esophagus (layers of tissue)

 

 

 

Upper Esophagus

Esophagus Epithelium