engleski

The ultrastructure and neuronal composition of the embryonic human spinal cord

The aim of this study was to find spatial and temporal course of the appearances of the different neuronal subtypes using different neuronal markers (calretinin, NF200, VR1 and CGRP) in the neural tube of the embryonic human spinal cord (SC). Developing human SC of 11 human conceptuses beetwen 5-10 developmental weeks (DW) was examined by light and electron microscopy and immunohistochemistry. Light and electron microscopy revealed different embryonic stages of recognizable structure of the SC. NF200, CGRP and VR1 positive cells we have found in the 5th-6th DW. NF200 was predominantly in the ventral part, indicating presence of motoneurons. As development process advanced, NF200 immunoreactive fibers were seen manly in the marginal layer. Expression of CGRP was intense during the all investigation periods, predominantly in the first one pointing to neural sensory differentiation, opposite to the last DW where CGRP reduction in the marginal layer was indicating the terminations of the sensory afferents. Expression of VR1 was highest in the intermediate layer, at the beginning and at the end of the investigated periods, pointing to VR1 spatial pattern in the visceral afferents in the grey matter, while the first signs of calretinin were found in the 9th-10th DW in the ventral part of the SC. Delineating the relationships between factors involved in processes of neuronal differentiation as well as spatial and temporal arrangement of SC interrelated neurons can provide a useful information about normal SC development as well as insight in possible causes of anomalies and disorders during embryonic life.

human embryo ; spinal cord ; neuronal differentiation ; calretinin ; NF200 ; VR1 ; CGRP

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