Prenatal Localization of the Dorsal Root Ganglion in Different Segments of the Normal Human Vertebral Column

STUDY DESIGN: Vertebral columns from 11 normal human fetuses (10-24 weeks of gestation) derived from spontaneous abortions were examined as part of the legal autopsy procedure including spinal cord analysis. OBJECTIVES: To study the localization of the dorsal root ganglion in the normal fetal spine and to relate the dorsal root ganglion location to the ossification of the vertebral bodies and vertebral arches. SUMMARY OF BACKGROUND DATA: The normal and pathologic ossification pattern of the fetal human spine has been studied. There has been no study addressing the localization of the dorsal root ganglion in normal and pathologic axial development. METHODS: The dorsal root ganglion were studied by using histology (horizontal sections) and morphometric measurement. RESULTS: The study showed: 1) The dorsal root ganglion appeared before ossification of the spine; 2) The dorsal root ganglion had an oval shape in all cases; 3) The longitudinal axis of dorsal root ganglion was directed anterolaterally in the cervical and lumbosacral segments and mainly laterally in the thoracic segment; 4) During development, the dorsal root ganglion changed position according to the body axis; and 5) The para-axial ossification protected the dorsal root ganglion differently in the different axial segments. CONCLUSIONS: The dorsal root ganglion appeared before ossification. The distance from the dorsal root ganglion to the body axis increased during development. In the different segments of the spine, different orientations and different locations of the dorsal root ganglion were observed in relation to osseous spine components. The results can be used as reference data for future studies on the dorsal root ganglion in pathologic spines.