MCAT Question A Day - 8/5/13 - Answer!
Which type of cellular connection would you expect to find between cells lining the intestines?
A. Desmosomes
B. Tight junctions
C. Gap junctions
D. Plasmodesmata
The correct answer is (B). Only tight junctions could prevent the unwanted passage of substances from the intestinal lumen into the blood or into the abdominopelvic cavity. The movement of materials from the intestinal lumen to the blood can only take place across cell membranes (via osmosis, diffusion, active transport, etc.) rather than around or between cells. The other cellular connections all allow some free passage of materials around and between cells.
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