Now when you look at
ganglia, it is important you
understand how to differentiate from a dorsal
root ganglia and another type of ganglia we
will see in a moment. This is the dorsal root
ganglion and what you see there are cell bodies,
somas of the sensory neuron. They are large
because as I have explained before.
Their axons project a long way to the periphery
and often a long way into the central nervous
system. I had showed you the reflex site but of
course when you prick your finger, you do
not just move your finger away very quickly
because of the reflex act, you remember it.
You feel the pain and that is because that
sensory neuron also communicates with other
neurons in the spinal cord and above in the
in the brain. So it is a large cell.
It has got a large length of axon to maintain.
Now what you see wrapped around these ganglion
cells are other small cells. These are called
satellite cells. And recall that these ganglion
cells, these sensory neurons do not have a
dendritic tree. They just a bipolar or a pseudounipolar
type arrangement, coming out and forming the
two axonal branches. So when you look at
sections of the dorsal root ganglion or sensory
ganglion, you often see satellite cells clustered
nicely around each of these sensory neuron
cell bodies because they can fit nicely around
and support these ganglion cells. Later on,
we will see that the ganglia associated with
the autonomic motor nerves do not have satellite
cells wrapped all the way around them because
of the dendritic trees that prevent that from
happening. And the big blob of material in
the middle of this section are the axons of
the sensory neurons.