Page 554 - Atlas of Histology with Functional Correlations

(10) and an outer longitudinal layer (14) of skeletal muscles, separated by

connective tissue (11). The outermost layer is the connective tissue adventitia
(8) with adipose tissue, nerves (13), a vein (9), and an artery (12).

FIGURE 14.3 ■ Upper esophagus (transverse section). Stain: hematoxylin and
eosin. Low magnification.

FIGURE 14.4 | Lower Esophagus (Transverse

Section)

This illustration shows the terminal portion of the esophagus near the stomach.

As in the upper esophagus, the mucosa (1) of the lower esophagus consists
of stratified squamous nonkeratinized epithelium (1a), the connective tissue

lamina propria (1b), and a smooth muscle layer muscularis mucosae (1c)
(transverse section). Also visible are the connective tissue papillae (2) that
indent the epithelium (1a) and a lymphatic nodule (3).

The submucosa (6) contains mucous acini of the esophageal glands proper

(5), their excretory ducts (4), and adipose tissue (7). In some regions of the
esophagus, these glands may be absent.

The major differences between the upper and lower esophagus are seen in
the next two layers. The muscularis externa (10) in the lower esophagus
consists of smooth muscle layers, an inner circular muscle layer (10a) and an

outer longitudinal muscle layer (10b). The outermost layer of the lower
esophagus is the serosa (8) or visceral peritoneum. Serosa (8) consists of a
connective tissue layer lined with a simple squamous layer mesothelium. In

contrast, the connective tissue adventitia surrounds the esophagus in the thoracic

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