Why are there no Nissl bodies in the axon?

Question

What could be the significance of not having Nissl bodies (endoplasmic reticulum) in the axon hillock (a part of the cyton) and axon? Does it have something to do with the processing of action potentials?What prevents Nissl bodies from entering the axon hillock even though they can enter dendrites (which are much narrower)?

Answer 1

So, there are two important ideas that distinguish the axon from the soma.

1. There are no rough ER (Nissl bodies) or free ribosomes in the axon
2. The protein composition of the axon membrane is different from that of the soma

Since there are no ribosomes in the axon, there is no protein synthesis. However, some dendrites synthesize proteins. So, all proteins in the axon must originate in the soma and are usually brought to the axon through axonal transport. The different proteins in the axon membrane allow it to send information over large distances.

Answer 2

Good thinking! Remember two things:

-the axon needs to be "unhindered" for electrical conduction

-organelles aren't just floating around in the cytoplasm - there is actually a rich cytoskeleton architecture! So organelles don't just drift away!