stratum spinosum of esophageal epithelium

The stratum spinosum of the esophageal epithelium is the second deepest layer of the stratified squamous epithelium that lines the esophagus. It is positioned directly above the stratum basale (basal layer) and consists of multiple layers of keratinocytes connected by strong intercellular junctions called desmosomes, which give the cells a characteristic spiny appearance in histological sections.

This layer is located within the esophageal mucosa, forming the layer immediately superficial to the stratum basale and beneath the more superficial layers of the stratified squamous epithelium. It extends across the full circumference of the esophageal lumen and is particularly prominent in the mid-esophagus.

The stratum spinosum is involved in providing structural integrity to the esophageal epithelium through its numerous desmosomal cell-cell junctions. Cells in this layer continue to undergo maturation as they migrate toward the surface. This layer also contains Langerhans cells, which are involved in immune surveillance within the esophageal mucosa.

Conditions such as reflux esophagitis, eosinophilic esophagitis, and viral infections (e.g., herpes simplex esophagitis) may be associated with changes in this layer, including intercellular edema (spongiosis), eosinophil infiltration, and ballooning degeneration of spinous cells. In Barrett's esophagus, the squamous epithelium, including this layer, is replaced by columnar metaplasia.

This layer is examined using histological analysis of esophageal biopsy specimens obtained during endoscopy. Hematoxylin and eosin staining allows identification of the layer and assessment of its thickness, cellular morphology, and the presence of inflammatory cells. Immunohistochemical markers such as p63 and CK5/6 can confirm the squamous epithelial nature of the cells.