Immunohistochemical and morphometrical development of the dorsal root ganglion as a neural crest derivative: comparison with the fetal CNS

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.

Minireview: summary of the initial development of the human nervous system

Ten points concerning the early development of the human nervous system and that are rarely appreciated in the literature are summarized. Opportune and discriminative comments on prenatal age are included, and a scheme illustrating the 10 points is provided.

Developmental changes of epidermal growth factor-like immunoreactivity in the human fetal brain

We investigated the immunohistochemical localization of epidermal growth factor (EGF) in the developing human brain from 6 weeks of gestation to 3 months postpartum. EGF-like immunoreactivity varied in its localization and intensity according to the stage of development. At 10 - 20 weeks of gestation, EGF-like immunoreactivity appeared in proliferating and migrating cells in the cerebrum, disappeared thereafter, and appeared again in cortical neurons after 27 weeks of gestation. Astrocytes also showed EGF-like immunoreactivity from 27 weeks of gestation. These results suggest developmental regulation of EGF expression in the human brain, suggesting its physiological role in both neuronal and glial cells.