2.2. Cortical synaptogenesis in the human developing brain in conditions of prenatal exposure to alcohol

As a lipotropic agent, ethanol, is able to change the basic physicochemical properties of cell membranes, which are reflected in the current synaptogenesis of the embryonic brain in order to establish the nature of this effect, we conducted the following studies.

In human embryonic brain in the early period—7–8th week of gestation, the desmosome-like contacts were represented as we observed. Contacting membranes are in their middle part of thickening, which both sides approach to each other, forming a fissure. In these places of the thickening, the membrane can be connected. Electron-dense material is in the field of adhesion. Contacts of this type are found between dendritic processes and neuronal cells. During the development of 9–10 weeks of pregnancy, these types of contacts are less frequent. Contacts with the presence of vesicular elements have been revealed. Synaptic vesicles were rounded and had a bright center, and the diameter of these vesicles was approximately 40 nm. The width of the synaptic space of immature synapses was approximately 20 nm. The length of the area of the sealing membrane reached 0.1–0.15 microns (Figure 7). In the transitional stage from synapse-like contacts to their true synaptic form, single synaptic vesicles were visualized near the presynaptic membrane. Such synapses are located mainly at the lower boundary of the intermediate layer of the cerebral cortex (Figures 8 and 9). They can already be considered functionally competent.

necessary components were found; from the mature synapses, their difference was the smaller number of synaptic vesicles. Synaptic contacts on neuroblasts and glioblasts have fewer synaptic vesicles compared to the synapses of the mature brain. All of the above features were inherent in

Molecular-Cellular Targets of the Pathogenetic Action of Ethanol in the Human Brain in Ontogenesis…

http://dx.doi.org/10.5772/intechopen.73333

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In the brain tissue of embryos and fetuses obtained from women suffering from alcoholism, a slowdown in the formation of synaptic structures was observed. Non-synaptic contacts in the samples of the main study group did not differ from those of control in the frequency of occurrence in the brain tissue and in its structure. The fully formed structure of the synaptic contacts is associated with the appearance of synaptic vesicles comparable with structure

The strong evidence we have obtained suggests that the developing brain is vulnerable to the pathogenic effects of ethanol. In the cells of the brain of embryos and fetuses from the main group of the study group, a slowing down of the process of synaptogenesis in comparison

Figure 10. Single synaptic vesicles in the formation of contact, the main group is a fetus of 12 weeks of development,

Figure 11. Single synaptic vesicles in the formation of contact, the main group is a fetus of 12 weeks of development,

both the control group and the main group of embryos and fetuses (Figures 10 and 11).

control; however, the area of the synapse was smaller [49].

magnified 60,000.

magnified 144,000.

Figure 7. Contact with uniformly thickened membranes. Main group, the fetus of 10–11 weeks. Magnification 160,000.

Figure 8. The emerging synapses in the cerebral cortex the intermediate layer brain. Main group, 12-week fetus. Magnification 40,000.

Figure 9. Completely formed functionally competent synapse. Main group, the fetus of 11–12 weeks. Magnification 70,000.

At the stage of fetal development 10–12 weeks, the number of synapses with relatively mature structures increased. They are located in the border of the ventricular and intermediate layers and in the intermediate layer of the cortical plate and nerve cells. In synaptic contacts, all the necessary components were found; from the mature synapses, their difference was the smaller number of synaptic vesicles. Synaptic contacts on neuroblasts and glioblasts have fewer synaptic vesicles compared to the synapses of the mature brain. All of the above features were inherent in both the control group and the main group of embryos and fetuses (Figures 10 and 11).

In the brain tissue of embryos and fetuses obtained from women suffering from alcoholism, a slowdown in the formation of synaptic structures was observed. Non-synaptic contacts in the samples of the main study group did not differ from those of control in the frequency of occurrence in the brain tissue and in its structure. The fully formed structure of the synaptic contacts is associated with the appearance of synaptic vesicles comparable with structure control; however, the area of the synapse was smaller [49].

The strong evidence we have obtained suggests that the developing brain is vulnerable to the pathogenic effects of ethanol. In the cells of the brain of embryos and fetuses from the main group of the study group, a slowing down of the process of synaptogenesis in comparison

Figure 10. Single synaptic vesicles in the formation of contact, the main group is a fetus of 12 weeks of development, magnified 60,000.

Figure 11. Single synaptic vesicles in the formation of contact, the main group is a fetus of 12 weeks of development, magnified 144,000.

At the stage of fetal development 10–12 weeks, the number of synapses with relatively mature structures increased. They are located in the border of the ventricular and intermediate layers and in the intermediate layer of the cortical plate and nerve cells. In synaptic contacts, all the

Figure 9. Completely formed functionally competent synapse. Main group, the fetus of 11–12 weeks. Magnification

Figure 7. Contact with uniformly thickened membranes. Main group, the fetus of 10–11 weeks. Magnification 160,000.

Figure 8. The emerging synapses in the cerebral cortex the intermediate layer brain. Main group, 12-week fetus. Magni-

fication 40,000.

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70,000.

with the norm was revealed, which can be critical for neurotransmitter processes in the developing human brain.
