engleski

Cell death in developing human spinal cord

Cell death in the developing human spinal cord was investigated in 5-12 week human conceptuses using immunohistochemical and TUNEL methods. Expression of pro-apoptotic (Fas-receptor, caspase-3) and anti-apoptotic (bcl-2) markers and marker for internucleosomal fragmentation (TUNEL) were analysed in the cranial (trunk) part and the caudal (tail) part of the human spinal cord. In the early developmental stages (5-6 weeks) of the cranial spinal cord, bcl-2 positive cells were seen in the ventricular zone and the roof plate, while in the caudal part they were surrounding the central lumen. Subsequently, bcl-2 expression appeared in the basal plates of the gray matter and in the spinal ganglia, and from the 7th week on it appeared in the intermediate horn of the gray matter as well. In the fetal period (9-12 weeks), bcl-2 expression ceased in the ventricular zone but appeared in the dorsal horns of the gray matter. In the trunk region TUNEL-positive cells characterized ventricular and mantle zones along the whole length of the spinal cord. Caspase-3 positive cells and Fas-receptor positive cells appeared only in the gray matter of the trunk segments of the spinal cord, while they were missing in the tail part. Caspase-3 dependant pathway, probably activated by Fas-receptor, seems to operate in the cranial part of the human spinal cord. In the tail part, cells seem to die by caspase-3 independant pathway. The interplay of pro-apoptotic and anti-apoptotic factors may be associated with cranial spinal cord morphogenesis, adjustment of cells number and selective survival of neurons, while in the tail region these factors cause massive cell death leding to regression the caudal spinal cord.

apoptosis ; caspase ; human embryo ; spinal cord ; Bcl-2

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