A picture review of basic esophageal histology...
There are four main layers of the esophagus
(from innermost luminal surface (part that food touches as it goes down) to the external surface)
1. Mucosa Innermost layer of the esophagus. Composed of luminal surface epithelium with underlying lamina propria and muscularis mucosae
2. Submucosa Contains connective tissue & lymphovascular channels
3. Muscularis propria Oriented as an inner circular and outer longitudinal muscle fibers
Upper 1/3= Skeletal muscle only
Middle 1/3= Mixed skeletal and smooth muscle
Distal 1/3= Smooth muscle only
4. Adventitia Outemost layer of the esophagus (NO serosal surface)
Normal findings to take note of:
There is no outer serosal surface which is why infections and cancers can spread rapidly to other sites...
The squamous epithelium should show nice maturation from the base to the surface (the basal layer should be only a few layers thick with larger, N:C ratio and get progressively smaller, more pink and lose their nucleus as they mature to the surface)
The vascular papillae should remain confined to the lower 1/3 of the epithelial thickness.
Esophageal glands contain acidic mucin that stains blue/basophilic on PAS/AB (similar to goblet cells seen in intestinal metaplasia).
Cardiac mucosa may be seen at the GE junction. These are columnar, foveolar type cells that contain apical cytoplasmic mucin (look very much like goblet cells), but are neutral & stain pink/magenta on PAS/AB. These are similar to "pseudogoblet" cells
A helpful tip to confirm you are in the esophagus- Look for esophageal ducts (used to transmit their secretions from the esophageal submucosal glands to the luminal surface). These are not present in stomach.