This is a low magnification of your colon slide showing simple columnar epithelium. The layer of purple nuclei is a marker for the base of the cell. The clear droplets containing mucus are secreted at the apex of the cell. Use these markers to define the boundaries of the epithelia.
The epithelium is usually polarized and has a nucleus at the base of each cell. The above slide is not from your slide set, but it is from the intestine. The mucous is stained blue and large droplets are seen in one cell type (Goblet cell). Also, it is spread along the surface of the epithelium facing the lumen (inside of the intestine). What is its function? Mark the basal and apical boundaries of this epithelium.
DUODENUM and JEJUNUM
In the photo from your duodenum slide an important apical surface specialization is
shown. This is called the brush border. What does it look like at the electron
microscopic level and what is its function? Also, can you see a droplet of mucous being
secreted? For more views of the intestinal epithelia see:
http://microanatomy.net/digestive/intestine.htm
