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Sensory neurones

COLLEEN M. SPECHT v102nq9f at ubvms.cc.buffalo.edu
Tue Jun 13 18:01:35 EST 1995


In article <3rl08k$107u at news.ccit.arizona.edu>, sfm at manduca.neurobio.arizona.edu (Stephen Matheson) writes:
>From article <3ris4k$65i at eldborg.rhi.hi.is>,
>by thoreys at rhi.hi.is (Thor Eysteinsson):
>>  DvorakH at starbase1.caltech.edu (Hannah Dvorak) writes:
>>>In article <8AB22AA.0E53000E32.uuout at dkb.dk>, lars.thomsen at dkb.dk (LARS
>>>THOMSEN) wrote:
>>>> I was wondering if any one remembered good examples of 
>>>> sensory neurones with the cell bodies close to the
>>>> location of the stimulus. 
>
>> I would say that nocireceptors (Pacinian corpuscles, Merkels disks,
>> etc.) were close to the stimulus,


>They are indeed, but they are not neurons.  As I seem to
>recall, these receptors are composed modified connective-tissue cells,
>and are *innervated* by sensory neurons with distant cell bodies.
>The generator potential occurs in the dendrite(s) of the sensory
>neuron.


while it is true that nociceptors have cell bodies which lie remote to the site
of stimulation, it isn't the case that nociceptors *are not* neurons.
nociceptors (A-delta and C-fibers) are indeed neurons with their cell
bodies lying remote of site of stimulation (this is according to the last
i read, which i believe was a modified gate-theory paper by melzack).

a receptor, by definition as the transductory apparatus, must be a neuron, and
*all* receptors are neurons.  there are, however, several cases where receptors
function in conjuntion with non-neural tissue (e.g., merkel's disc), but the
non-neural component is *not* the receptor.

>Similarly, gustatory cells in taste buds are made of modified
>epithelial cells (I think), and again are innervated by cranial
>sensory neurons in somewhat distant ganglia.

again, gustatory receptors are innervated by the 7th cranial (as already
alluded to) but are indeed the neuron/receptor that converts the chemical
stimulus into an electrical message.  they are packed in taste buds, but i
would say that they are proximal to the stimulus.  gustatory receptors are
neurons.



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