Further studies on Barretts mucosa in baboons: metaplastic glandular cells produce sialomucin

Abstract

Background: In humans and in baboons, protracted gastro-esophageal reflux (GER) transforms the squamous-lined esophagus into columnar-lined (that is Barrett's mucosa, BM). Alcian blue stain (AB) is used to evidence sialomucin-producing goblet cells in human BM.

Aim: To assess the frequency and distribution of sialomucin-producing cells in BM in baboons.

Materials and methods: Sections from 137 consecutive baboon esophagi were alternatively stained with hematoxylin-eosin (H&E) and with AB (pH 2.5), without counterstain.

Results: Out of 137 baboons, 131 (95.6%) had BM. Columnar and intramucosal glandular cells produced sialomucin in all 131 of these animals. Many BM cells were ballooned and filled with sialomucins, despite goblet cells not being found in H&E sections.

Conclusion: In humans, protracted GER is a disease requiring medication that may lead to BM; AB stains mainly goblet cells and occasional columnar cells in BM. In baboons, in contrast, BM is a natural postnatal process of adaptation to GER, triggered by regurgitation and rumination. AB stains all columnar and intra-mucosal glandular cells. Sialomucin-overstuffed cells were more frequent and larger in baboons than in humans. The extra load of sialomucin in BM might be an integrated part of the postnatal life-long process of adaptation to regurgitation and rumination in baboons.

Figure 1

Low power-view of the esophagus in a baboon showing columnar-lined glandular mucosa and squamous cell epithelium (arrow) (H&E, ×2).

Figure 2

Columnar-lined glandular mucosa of the esophagus in a baboon, showing sialomucin-positive cells, both along the surface epithelium as well as in the epithelium of the glands (Alcian blue, pH 2.5, without counterstain, ×10).

Figure 3

Columnar-lined glandular mucosa of the esophagus in a baboon, showing sialomucin-positive cells, both along the surface epithelium as well as in the epithelium of the glands. In contrast, the squamous epithelium (arrows) remained unstained (Alcian blue, pH 2.5, without counterstain, ×4).

Figure 4

Columnar-lined glandular mucosa of the esophagus in a baboon, demonstrating the variation in size of sialomucin-positive cells. Some cells show a ballooned cytoplasm, but the corresponding H&E-stained sections revealed no classical goblet cells (Alcian blue, pH 2.5, without counterstain, ×40).