SC - Simple Columnar Epithelieum
MV- Short apical microvilli
LP- Lamina Propina
ME- Muscularis Externis
The Gall Bladder lacks a submucosa so the lamina propina lies directly between the folded mucosa and the smooth muscle of the muscularis externis. The Gall Bladder also has short apical micro villi which is evident where it is labeled in the picture but not all over the slide.
Peyer's Patches are lymphatic tissue located in the wall of the ileum.