Embryological study of the spinal dura and its attachment into the vertebral canal

BackgroundThis observational study reviews the development of the spinal dura and its attachment into the vertebral canal.MethodsMicroscopic investigations have been carried out on sections of a 27-mm crown-rump length (CRL) embryo, a 100-mm CRL fetus and a nearly 7-month-old fetus.ResultsThe results appear very consistent with those present in the literature. The 27-mm CRL embryo's dura lamella still appears strongly attached to the vertebral body as well as to the laminae. Dorsally it forms part of the membrana reuniens dorsalis. Only on upper thoracic and cervical levels several sections clearly show a releasing anterolateral dura lamella; however, a close attachment remains in the very center. On sacral canal level, sections of the 100-mm CRL fetus clearly show connective tissue strands in the laterocaudal direction, linking the dural sac and the surrounding sacral canal. In almost every region, the abdominal sections of the 7-month-old fetus show a linkage between dura mater and posterior longitudinal ligament. This linkage fluctuates from fibrous structures to a wide and mostly stratified attachment providing a close contact between both structures. In the intervertebral foramen region, several sections show a structure of connective tissue, covering the foramen laterally from the spinal ganglion and having contacts with laminae and disci.ConclusionsThe attachments perceived between spinal dura and its surroundings may be considered to be the remains of an original unitary tissue, which will differentiate into full-grown ligamental structures according to the unique functional heritage of the individual. These epidural ligaments may have to play an important physiological and pathophysiological role in the human body.