engleski

Expression pattern of phox2b, NF200 and IB4 markers in the developing human spinal ganglia

In this study we investigated developmental pattern of the neural crest cells towards first appearing of the neuronal subtypes in the spinal ganglia. The aim of the study was to estimate the spatial and temporal appearance of the neural crest cells in the spinal ganglia and their differentiation into neuronal subtypes. Expression of the neural crest cells and neuronal subtypes markers were studied in 10 human embryos and fetuses, ranging in age between the 5th and 10th developmental week. The differentiation of the neurons was analysed using immunohistochemistry and immunofluorescence methods on paraffin sections. Quantification of positive cells was performed counting the ratio of positive cells in the total cell number in squares of 50μm × 50μm at 40× magnifications. Data were expressed as mean ± SD and the difference between dorsal and ventral part of the spinal ganglia were analysed by the Mann-Whitney test and t-test. The phox2b marker (for early differentiated neurons) had the strongest expression in the 5/6th developmental week (73% of positive cells), gradually decreasing to 59% in the 9/10th developmental week. The number of phox2b positive cells was higher in the dorsal parts of the spinal ganglia than in the ventral parts, especially in the 7/8th week (t-test, p=0.007). First NF200 (mechanoreceptors) and IB4 positive neurons (nociceptors), appeared already in the 5/6th developmental week (9% and 7%, respectively). Their number subsequently increased to 22% and 24% in the foetal period. The number of NF200 positive cells was higher in the ventral parts of the spinal ganglia than in the dorsal parts especially during 5/6th and 9/10th developmental week (Mann-Whitney, p=0, 040 and p=0, 003 respectively). Our results indicate the high potential of early differentiated neuronal cells, which slightly decreased with progression of spinal ganglia differentiation. On the contrary, the number of neuronal subtypes displayed increasing differentiation at later developmental stages. The great diversity of phenotypic expression found in the spinal ganglia neurons is the result of a wide variety of influences, occurring at different stages of development in a large potential repertory present in these neurons.

spinal ganglia; human embryo; phox2b; IB4; NF200

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