Nestin expression in glial and neuronal progenitors of the developing human spinal ganglia

Expression of the neural crest marker nestin was studied in glial and neuronal progenitors of developing human spinal ganglia using immunohistochemistry in 10 conceptuses, 5-10 weeks old. Quantification was performed by counting the ratio of positive cells in the total cell number, expressed as mean + or - SD and by the Mann-Whitney test. Strong expression of nestin in the 5th-6th developmental week (56%) decreased to 49% in the foetal period. During the same period, number of PGP9.5-positive cells increased from 38% to 42%. At earliest stages, the number of cells expressing GFAP was two folds higher (21%) than S100 (11%). During further development, their number nearly levelled (23% and 28%, respectively), and finally reached level of 25% for GFAP and 40% for S100. While expression of nestin was constantly higher in the dorsal parts of spinal ganglia, number of PGP9.5-, GFAP- and S100-positive cells was higher in their ventral parts, thus indicating ventral to dorsal direction of spinal ganglia differentiation. Co-localization of nestin and GFAP or nestin and S100 was observed during the whole investigate period, while PGP9.5 did not co-localize with nestin. Some ganglion cells simultaneously co-expressing GFAP and S100 might be satellite cells and immature Schwann cells. We suggest that some nestin-positive cells might be capable to differentiate into neurons during the earliest stages of development. Gangliogenesis seems to be important process during the whole ganglion development. Continuous presence of neural crest cells during development might be important in regenerative processes following damage of the spinal ganglia.