OBJECTIVETo study growth characteristics of neural stem cells (NSCs) from subventricular zone (SVZ) of the different human fetal brain at different gestational age and to provide experimental and theoretical evidences for clinical application of NSCs for treatment of certain diseases.

METHODSNinety human embryos at gestational age 16 - 36 weeks were collected and were divided into six groups according to gestational age: 16 w, 20 w, 24 w, 28 w, 32 w and 36 w. Each group had 15 embryos and brain tissues were taken from each embryo's SVZ. All subjects had congenital heart disease or digestive tract abnormity diagnosed with B ultrasound at antepartum, but none had abnormal development of brain. Pregnant mother and her husband desire termination of pregnancy. The morphology, existing mode and the number of neural stem cells in subventricular zone were examined with immunohistochemical method. The NSCs in subventricular zone were cultured, passaged and differentiated with cell culture technique, then were identified with immunohistochemical method.

RESULTSNSCs in SVZ from the different human fetal brain existed in a scattered manner in the network formed by stellate cells, NSCs had round, ellipse and fusiform shape, especially in stellate shape. NSCs had larger and smaller size and distributed in dense or scattered forms, each having zero to two enations, most had one or two. NSCs had less cytoplasm. The nucli of the NSCs had a round shape with loose chromatin and 1 - 4 nucleoli. Most of NSCs existed in singular scattered form, some of them showed symmetrical or asymmetrical division, some of them showed synaptic connection with other NSCs. The number of NSCs in SVZ from groups with different fetal age decreased with increasing gestational age (chi(2) = 4644.602, P < 0.01). NSCs in SVZ from the different human fetal brain cultured with serum-free medium formed typical neurospheres in suspension. The cells could be passaged continuously, and could express nestin antigen. Serum-contained medium induced neural stem cells to differentiate and express specific antigens of neuron, astrocyte and oligodendrocyte.

CONCLUSIONSNSCs existed in SVZ of human embryos at different gestational age. There are differences in morphology, existing pattern and the number of NSCs in SVZ at different gestational age. NSCs in SVZ at different gestational age may be cultured in vitro.