engleski

Histochemical reorganizational processes in the human fetal cingulate gyrus during midgestation

Since the transient zones of future cingulate gyrus (enlarged marginal and somewhat modest subplate zone) differ in comparison to future neocortical regions, we suppose some differences in timing of histogenetic processes (neuronal and glial migration, cells and procesusses differentiation) and reorganization. As a result, we expect spatial- temporal expression patterns of neuronal, glial and extracellular immunohistochemical markers among transient zones in the future anterior and midcingulate region to differ from other limbic as well as neocortical regions of the telencephalic wall. We used 27 post mortem fetal human brains, aged from 17 post conception weeks (PCW) to 40 PCW, stained by Nissl method, neuronal (microtubule associate protein, MAP2), glial (glial fibrillary acidic protein, GFAP), and extracellular (neuroan, NCAN and tenascin, TNC) immunohistochemical markers. A fine, discreet MAP2 immunoreactive neurons are visible in the cortical plate of the future cingulate gyrus well before 20 PCW, but pyramidal- like cellular staining appears clearly at 20 PCW. The early signs of lamination of the cortical plate (CP) of cingulate gyrus are visible at 33 PCW, accompanied by the appearance of mature astrocytes, shown by GFAP. Significant differences between the cingulate gyrus and other telencephalic regions were found in TNC immunoreactivity during mid-gestation. Compared to other regions of the telecephalon, expression of TNC was upregulated in the marginal zone (MZ) and downregulated in the subplate zone (SP) of the presumptive cingulate gyrus. Also, TNC immunoreactivity in the SP showed decreasing gradient from deep to superficial and also differences in the timing and level of expression from anterior to posterior cingulate areas, appearing later in mid and posterior areas. The NCAN, a proteoglycan proven to play a number of roles in the brain development, is expressed in the CP of the future cingulate region stronger than in the rest of the medial telencephalic throughout the second half of gestation. Expressions of TNC and NCAN coincide in the intermediate zone from 17 PCW until 28 PCW and in the CP from 20 PCW until 33 PCW. These findings suggest that studied extracellular molecules might play a role in autocrine astrocyte/oligodendrocyte differentiation and possible axon guidance for projecting subplate neurons on one side and ingrowth of afferents on the other side

limbic cortex ; cortico-cortical connections ; tenascin C ; MAP2

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