Characteristics of human cortical pyramidal neuron development during the second gestational trimester

Author： Krasnoshchekova E. Zykin P. Tkachenko L. Smolina T.

ISSN： 0362-1197

Source： Human Physiology, Vol.36, Iss.4, 2010-07, pp. : 427-432

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Abstract

Prenatal ontogeny of the human neocortex exhibits specific characteristics that make its organization unique. Therefore, experimental data obtained on animal models cannot be extrapolated to human cortex morphogenesis during the middle and late gestational periods. Characteristics of the development of cortical pyramidal neurons of the human brain were studied in the brains of eight fetuses at gestational ages between 16 and 26 weeks. Immunohistochemical labeling of neurons was performed using antibodies against microtubule associated protein 2 (MAP2), a structural protein of microtubules. Expression of this protein marks the beginning of dendrogenesis. MAP2 is mainly located in the neuron body and dendrites, which allowed the neuron morphotype and location in specific cortical layers to be determined. It was shown that MAP2-immunopositive neurons were identifiable in embryonic cortical layer eV as early as the 18th gestational week. By the 25th gestational week, two populations of pyramidal neurons were discernible in the cortical plate, one of them located in layer eV and the other, in layer eIII, which developed later. Since differentiating neurons are known to be more vulnerable than neuroblasts and mature neurons, these results suggest that critical periods for corticofugal and corticocortical populations of pyramidal cells occur at different stages of the second gestational trimester.