engleski

Spatiotemporal expression pattern of the neuronal markers in the developing human spinal cord

We have investigated the spatiotemporal appearances of the different neuronal markers in the different parts of the developing human spinal cord (SC) in 12 human conceptuses (developmental weeks, DW 5–10) by immunohistochemical and immunofluorescence methods. In the developing SC a dorsoventral (DV) organization can be seen. CV neural wall is consists of three layers, marginal, intermediate and ventricular one. Between roof (placed dorsally) and floor plate (placed ventrally), an abundant of neuroblasts showing a DV organization were found, pointing to anatomically segregated motor and sensory spinal neurons. Dorsal area of the SC is sensory area, while motor neurons and proprioceptors are found in the ventral part. The motoneurons are the first cells that occur, followed by interneurons and finally sensory and autonomic neurons. Intermediate and large neurons are predominantly mechanoreceptors and proprioceptors and could be identified by neurofilament NF200. Small-diameter unmyelinated nociceptive peptidergic neurons can be recognized by expression of neuronal marker calcitonin gene- related peptide (CGRP). The vanilloid receptor (VR1) is expressed by primary afferent nociceptor neurons which are peptidergic small diameter type cells, while calretinin has important role in somatosensory and proprioceptive pathways. In the 5th-6th DW, calretinin first appears in the marginal layer of the developing SC, dorsally, while in the 7th-8th DW it was found in the intermediate layer. In the 9th-10th DW, calretinin was found also in the ventral part. During the 5th-6th DW, NF200 positive cells were found in the intermediate layer ventrally and in the cells lining the marginal layer, while in 392 the 7th-8th DW NF200 showed moderate expression in the ventricular layer also ventrally, as well as in the intermediate layer dorsally. Co- localisation with DAPI was found only in the ventricular layer. In the 9th-10th DW, NF200 positive cells were predominantly distributed in the marginal layer. CGRP was highly expressed in the intermediate and ventricular layer, as well as in lining cells of the marginal layer during the 5th-6th DW. By the end of the 7th-8th DW, strong expression of the CGRP was seen in the cells lining the central canal, while in the 9th-10th DW it was predominantly expressed in the intermediate layer and strongly co-localised with DAPI dorsally. During the 5th-6th DW, VR1 positive expression was found in the intermediate layer as well in the cells lining the marginal one, while in the 7th-8th DW it was evenly distributed in both, intermediate and ventricular layer. In the 9th-10th DW, strong expression of VR1 was found in intermediate layer and in the cells lining the central canal, also showing strong co- localisation with DAPI within all three layers. Spatial and temporal expression pattern of these neuronal markers with their possible changes during the embryogenesis provide important information for normal spinal cord development.

human spinal cord development, calretinin, NF200, CGRP, VR1

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