Neuron Growth

[biologisthegde]

[color=darkblue]Hello,

During early growth by which mechanism one part of the neuron becomes axon and another part dendrites? Any answer?

[biostudent84]

An axon pretty much is an extension of a dendrite. There is nothing saying a neuron can only have one axon...it just turns out to be that way most of the time. Two axons would allow a nerve to fire in two different directions. Since nerve tissue only needs to fire in one direction, one axon saves the energy required to grow more.

Kyle

[MrMistery]

I have to contradict you on that one kyle. I looked in 12 biology books and all of them said the same thing- a neuron may have none, one, two or many dentrites but it can only have one axon. Not 0, not 2. Maybe the latest reasearch hasn't reached my country but here this is how people know it
regards,

[adidasty]

as the neuron differentiates during development, it can develop many number of different traits depending on its relative location. many CNS undifferentiated cells develop into interneurons which have many dendrites and one axon of course because vastly multicellular communication is vital. however, some neurons located in other areas may not have any dendrites! they all however have one axon on which electric potential is generated. logically, more than one axon on a neuron would make for a greater need of Na+, Cl-, K+ ionic concentrations and the presence of multiple axons may make the action potential weaker in some respects.

[biostudent84]

There are some...not many, but some. They are called "multipolar neurons"

http://iserver.saddleback.cc.ca.us/facu ... rvous.html

[MrMistery]

right on, biostudent. In my book(which i am looking at right now) it says that multipolar newrons are located in the cerebral cortex. They can be either piramid or star shaped.
By the way, if you are wondering why i looked in the book: I did know that . I just wanted to make sure

[adidasty]

good research biostudent, im glad to be informed of these interesting cells.

[biostudent84]

Just remember....this is one of those things. It's an exception to the rule. And the rule is that all neurons have one axon. =)

[MrMistery]

Biostudent, multipolar newrons, the ones in the cortex have more dentrites.
The newrons without dentrites are unipolar newrons and are located in the retina(the cells with cones and sticks)

[adidasty]

if multipolar neurons are what they call the interneurons of the cortex, then they definitely have an extraordinary amount of dendrites.

unipolar neurons....yeah the rods and cones....definitely extremely specialized