Reflections on notochordal differentiation arising from a study of chordomas.

This study of thirteen cases of chordoma serves to emphasize the occurrence of three different histological patterns; classical, seven; chondroid, three; and intermediate or mesenchymal, three. The study also suggests that more adequate sampling of these tumours detects the chondroid variant more readily. These varying patterns of differentiation in tumours of notochordal origin suggest that the parent tissue may have the potential to develop along similar lines in the embryo. Thus mesenchymal and cartilaginous tissue formed from notochordal cells could contribute to the formation of the nucleus pulposus and inner portion of the intervertebral disc cartilages. This concept contrasts with the previously held view that the notochord atrophies at an early stage in embryonic development.