The apex of the posterior grey column, one of the three grey columns of the spinal cord, is capped by a V-shaped or crescentic mass of translucent, gelatinous neuroglia, termed the substantia gelatinosa of Rolando (or SGR) (or gelatinous substance of posterior horn of spinal cord), which contains both neuroglia cells, and small neurons.

Many μ and κ-opioid receptors, presynaptic and postsynaptic, are found on these nerve cells; they can be targeted to manage pain of distal origin.

For instance, neuraxial administration of opioids results in analgesia primarily by action in the dorsal horn of the spinal cord in the substantia gelatinosa where they inhibit release of excitatory neurotransmitters such as substance P and glutamate and inhibit afferent neural transmission to the brain from incoming peripheral pain neurons via hyperpolarization of postsynaptic neurons.

Thus, the cell bodies located here are part of the neural pathway conveying slowly conducting, poorly localized pain sensation.

However, some A delta fibers (carrying fast, localized pain sensation) also terminate in the substantia gelatinosa, mostly via axons passing through this area to the nucleus proprius.

Fibers synapsing on these laminae that release peptides SST and GDNF may be part of a pathway that inhibits pain signaling.