Embryological study of the spinal ligaments in human fetuses.

We studied embryological development of the human spinal ligaments by dissecting 25 fetuses that ranged from 6 to 24 weeks of gestational age. At 6 and 7 weeks, the spine consisted of light zones and dark zones. The light zones were hypocellular and corresponded to vertebral bodies. The dark zones were hypercellular and corresponded to intervertebral disks. The anterior longitudinal ligament was identified at the gestational age of 8 weeks. At 10 weeks, the posterior longitudinal ligament was detected. At 12 weeks, laminae, the ligamentum flavum, and an ossification center were identified. At 15 weeks, fibers of the ligamentum flavum became clearer, but they were not as well as stained as the adult ligamentum flavum. The enthesis of the ligaments in the human fetuses was not completely identical to that in adults.