There is much debate over whether the gastric cardia exists from birth as a normal structure or is a metaplastic structure that develops as the result of gastroesophageal reflux disease. This question has become a matter of concern since the incidence of adenocarcinoma at the gastroesophageal junction has been increasing rapidly in the Western world for more than 2 decades. Various groups of investigators have tried to clarify this matter by examining the histology of the gastroesophageal junction in autopsy cases, and there have been striking discrepancies in their findings. In one group, it was observed that cardiac mucosa was present in all pediatric autopsies. On the contrary, another group concluded that pure cardiac mucosa was absent in 56% of their autopsy cases.
Without regard to the definition of the cardiac mucosa, we focused on the distance between the squamocolumnar junction and the most proximal parietal cells to elucidate the histologic features of the gastroesophageal junction on the gastric side.
The entire gastroesophageal junction and the proximal part of the stomach from 23 fetal and pediatric autopsies were mapped. We measured the distance from the squamocolumnar junction to the most proximal parietal cells identified. The extent of the transitional zone, defined as the mucosa between the squamocolumnar junction and the fundic mucosa, was also evaluated.
The transitional zone was identified in 78% of cases, and it always harbored some scattered parietal cells in mucous glands. The parietal cells were consistently identified adjacent to the squamocolumnar junction in all cases. Although the transitional zone in fetal stomach was usually composed of several pits of foveolar epithelium without glandular portions, it contained glandular structures in the pediatric cases.
The mucosa composed of pure mucous cells does not exist as a normal developmental structure.