The Adult Apical Ligament of the Dens Does Not Contain Notochordal Tissue: Application to Better Understanding the Origins of Skull Base Chordomas

Abstract Introduction The apical ligament has long been reported to contain notochord remnants and thus might serve as a site of origin of chordoma formation at the skull base. However, to our knowledge, the histological study of the apical ligament using histological staining specific for notochordal tissue has not been previously performed. Therefore, the current study was undertaken. Methods: Fifteen apical ligament samples underwent histological examination with specific markers for notochordal differentiation. Results: Across all samples, there was no indication of any notochordal remnants. Conclusions: Based on our cadaveric study, the apical ligament does not contain notochord tissue and in adults, should not be considered a remnant of this structure. Moreover, it is unlikely that the apical ligament gives rise to chordomas at the craniocervical junction under normal circumstances.