(C23-25) SLIDE 43: Cardioesophageal junction, longitudinal section (H&E)

This section is somewhat oblique, and in places one can see two cuts through the esophagus. The muscularis mucosae shows well. The muscularis externa, especially the inner circular layer, is considerably enlarged to form the cardiac sphincter (C23 cs). The myenteric plexus is also apparent (24 center). Slightly caudal to this region the mucosa undergoes an abrupt change to that of the cardiac region of the stomach (C25 arrow). You should restrict your study to the first 10-15 pits at this time which are in the cardiac region, and ignore the transition to the fundic region. The basic orientation of all the cardiac glands is essentially similar: a surface epithelium of simple columnar cells extending down into the pits, from the bottom of which the adenomeres continue. In this region, the distinction between pits and adenomeres can be made, but the cells in the two regions are very similar on this slide. Just internal to the muscularis mucosae is a stout, amorphous membrane (elastin?) (C25 am) that is apparent in this (unknown) species but is not found in people. The submucosa is quite loose, and the submucosal plexus can occasionally be seen.