A spinal ganglion (40X)
A ganglion is the term for an accumulation of nerve cells outside the central nervous system. The spinal ganglia are found just periperally to where the ventral and dorsal (front and back) nerve roots merge into a spinal nerve, the dorsal root has a coil-shaped thickening. This is the spinal ganglion and that is what you see here.
There are many large nerve cell bodies (neurons) and bundles of peripheral nerve fibers (axons) cut longitudinally. At the top and bottom of the image you can see a connective tissue capsule.