[Features of human cortical pyramidal neurons development during second gestational trimester]

Prenatal ontogeny of human neocortex have distinctive features that make it unique. Experimental data obtained on animal models could not be easily extrapolated on human corticogenesis of middle and late gestational period. Our research was aimed at features of human cortical pyramidal neurons development within 16-26 gestational weeks. Material was obtained during legal autopsies. Neurons were marked using indirect immunofluorescence with primary antibodies against phosphorylated a nd dephosphorylated microtubule associated protein MAP2.Expression of this protein marks the beginning of dendrogenesis. Morphotype and position of neuron within embryonic cortical layers could be easily identified due to abundance of MAP2 in neuron body and dendrites. It was shown, that MAP2 positive neurons are identifiable in embryonic cortical layer eV as early as 18th gestational week. At 25th gestational week two populations of pyramidal neurons are apparent inside cortical plate. In addition to layer eV neurons that have had differentiated earlier, layer eIII neurons appears. According to fact that differentiating neurons are more vulnerable to damaging factors than neuroblasts and mature neurons, our results suggest that critical periods for cortico-cortical and corticofugal populations of pyramidal cells occurs at different stages of second gestational trimester.