OBJECTIVETo observe the morphological changes during development of the ventricular zone (VZ) and subventricular zone (SVZ) of human fetus and the distribution pattern of neural stem cells in the VA and SVZ.

METHODSHuman fetuses at the gestational ages of 9-11 weeks, 14-16 weeks, 22-24 weeks and 32-36 weeks were collected, and the brain sections of the VZ/SVZ under the frontal lobe were examined for cytoarchitecture and distribution of nestin-positive cells with HE staining, immunohistochemistry or immunofluorescence.

RESULTSThe thickness of VZ underwent no significant changes at the gestational ages of 9-24 weeks (P>0.05) and became obviously thinner at 32 weeks (P<0.05), while the thickness of SVZ increased during 9-24 weeks (P<0.05) without obvious thinning at 32 weeks (P>0.05). VZ was thicker than SVZ at 9-11 weeks but became markedly thinner than SVZ after 14 weeks (P<0.05). The VZ contained denser cells than SVZ and showed a distinct boundary between the VZ and SVZ. Large numbers of nestin-positive cells were detected in the VZ and SVZ, and nestin immunoreactivity was found primarily in the cell processes and occasionally in the soma. Some nestin-positive cells in the SVZ had 1-3 processes. Nestin immunoreactivity in the VZ and SVZ gradually grew weak with development. The cells positive for both nestin and Ki67 were located mainly in the inner zone of the VZ and throughout the SVZ, where some nestin-positive but Ki67-negative cells were also found.

CONCLUSIONThe SVZ fully extends and the neural stem cells in the VZ/SVZ can be morphologically heterogeneous during the development of fetal human brain.