Esophagus -- conducts food from oral cavity to stomach. Start by reviewing the general plan of the gastrointestinal tract (Fig. 15-2), noting especially the four major layers which are clearly seen in the esophagus:

• Mucosa
  • The epithelial lining of various types
  • Lamina propria of connective tissue
  • Thin muscularis mucosae of smooth muscle
• Submucosa containing blood vessels, lymphatics, and nerves
• Muscularis: two thick layers of smooth muscle for peristalsis
• Adventitia or serosa: outer connective tissue covering

Examine the preserved-mounted specimens of the various regions of the digestive tract, noting the macroscopic features (stomach rugae, plicae circulares, etc.) for correlation with the slides you will also study.

Examine a transverse section of the esophagus (slide 66 or 43). Identify the various layers and sublayers indicated in the general plan (Fig. 15-14)

• Note the epithelial type of the lining,
• The presence of small mucous glands
• Any lymphoid nodules present, and
• Autonomic ganglia and nerves of the myenteric plexus (Fig. 15-35b).

What would the muscularis in the upper region of the esophagus show differently?

Let's consider the muscular layers in more detail.