This slide presents some peculiar difficulties, but also abundant clues for correct identification.

Note that a rather thin tissue specimen has been folded (follow the dotted line).

This leads to a rather confusing appearance, at least in the region indicated by number 1.

However, if you use your imagination to "unfold" the tissue, you should easily see three distinct layers, shown in the enlargement below from region number 2.  Only one organ system has such distinct layers.

• A mucosa
• B submucosa
• C two-layered muscularis

Although most of the surface epithelium has been lost (a fairly typical post-mortem change), some characteristic epithelium can still be easily seen in protected sites deep in the mucosa. The shape of the missing epithelium may be reconstructed by using your mind's eye to cover the lamina propria with epithelium similar to that which remains.

Use the three distinct layers, the appearance of the remaining epithelium, and the charactistic shape of the lamina propria and of the submucosa to deduce which region of which organ system this must be.

No more hints.