Expression pattern of NeuN and GFAP during human fetal spinal cord development

The development of the human embryonic spinal cord is very complicated, and many cell types are involved in the process. However, the morphological characteristics of neuronal and glial cells during the development of the human fetal spinal cord have not been described. We investigated the systemic distributions and expression pattern of the cell type-specific markers Neuron-specific nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP) during the development of the human fetal spinal cord, in order to clarify the detailed developmental changes of neuronal and glial cells in chronological and spatial aspects. A total of 35 fetuses, aged 3 weeks to 8 months of gestation (E3W-E8M), were studied. The markers used for immunohistochemical study were NeuN and GFAP. The intracellular makers NeuN and GFAP were widely detected expression in different structures and cells during the development of the human fetal spinal cord, including the following: central canal, neuroepithelial layer, internal limiting membrane, mantle layer, marginal layer, basal plate, alar plate, ependymal layer, gray matter, white matter, neuron, astrocytes, and nerve fibers. However, there was an absence of GFAP in astrocytes during early fetal spinal cord development until E9W, and the appearance of GFAP-positive reactivity was later than that of neurons. We consider that NeuN and GFAP can be used to identify neuronal and glial cells during the development of the human fetal spinal cord, and their distribution differs both chronologically and spatially. These characteristic expression patterns would give us a clue to better understand the developmental characteristics of the human spinal cord.