Substance P- and CGRP-immunoreactive nerves in bone.

The present study demonstrates the occurrence of substance P (SP)- and calcitonin gene related peptide (CGRP)-immunoreactive nerve fibres in bone, bone marrow, periosteum, synovial membrane and soft tissues adjacent to the bone. The distribution pattern of the two types of nerves was similar, although the CGRP-positive fibres generally were more numerous. Both types of nerves were particularly abundant near the epiphyseal plate, in the bone marrow of patella and epiphyses, and in the periosteum. Many SP- and CGRP-immunoreactive fibres were also observed around blood vessels.