Epithelia: Simple squamous - identification

Click image to show/hide labels.

This is a section from the liver - can you spot the simple epithelium?

Click image to show/hide labels.

This is another section from the liver - try to spot the simple squamous epithelium.

Hint - the red cells in the middle are red blood cells (erythrocytes) - so they must be in a blood vessel, which is lined with endothelium

Question: what type of cells make up this endothelium?