Method of Reduction Background Fluorescence in Human Fetal Brain Tissue and Quantitative Estimate of the Effect of Photobleaching.

We developed a method of reducing the background fluorescence of samples made from formalin-fixed and paraffin-embedded blocks of the brain of the second-trimester human fetuses. For reducing excess background fluorescence, the samples were subjected to photobleaching using an LED lamp with blue and red emission peaks in the range of visible spectrum in a construction of an original design. The decrease in the background autofluorescence was checked by measuring the intensity of the emitted background fluorescence of the samples and relative abundance of immunopositive structures after immunohistochemical staining. It was found that the proposed method reliably reduced the background fluorescence of the samples, which improved the quality of multicolor immunofluorescence images of the cerebral cortex.

[Prenatal ontogenesis of the human brain cortex temporal area].

Prenatal ontogenesis of temporal areas of the human cortex was studied. In the fetal cortex at the gestational age of 16-18 weeks three zones can be distinguished: marginal zone (eI layer), cortex plate and subplate. At 20-26 weeks cortex plate is divided into following layers: eII, eIII, eIV, eV and eVI, with "efferent" complex of layers being wider than "associative" one. The subplate neurons are eliminated in the fetus at 27-33 weeks, when "associative" complex composes over 50 per cent of the cortex thickness. The subplate has been identified by positive correlation between layer eII and the upper subplate layer spu cell density.