Expression of TENASCIN-C in the Subplate Zone of the Medial Telencephalic Wall During Prenatal Development of the Human Brain

Ovaj rad opisuje izražaj proteoglikana tenascina-C (TN-C) u prolaznom sloju pod kortikalnom ploĉom (eng. subplate zone, SP) u razdoblju od 12. do 40. tjedna gestacije (t.g.) primjenom indirektne imunohistokemijske metode na postmortalnom moždanom tkivu. TN-C eksprimiran je u dubinskom podsloju SP-a poĉevši od 16. t.g. pa sve do 40. t.g., dok u površinskom dijelu SP-a nije zamijećena ekspresija. Osim u SP-u njegov izražaj vidljiv je u intermedijarnoj zoni (IZ-u) i u kortikalnoj ploĉi (CP-u). U sve tri embrionalne zone vidljive su razlike izmeĊu frontalne, centralne i parijetalne regije telencefalona. Prva ekspresija zabilježena je u IZ-u u 12. t.g., a potom u SP-u i CP-u u 16. t.g. Frontalno u SP-u izražaj postepeno slabi do 20. t.g., nakon ĉega je sporadiĉno vrlo slabo vidljiv ili nije zamjetan. U 25. t.g. izražaj se ponovno javlja te ostaje slabim do kraja gestacije. Centralno je izražaj slab tijekom ranog i srednjeg fetalnog razdoblja, a u kasnom postaje umjerena intenziteta te se tako zadržava do kraja gestacije. Parijetalno se izražaj javlja tek sredinom srednjeg fetalnog razdoblja, a već u kasnom opet nestaje. Izražaj tenascina-C nije moguće povezati s urastanjem aferenata iz talamusa i bazalnog telencefalona. Moguća uloga mu je u autokrinom poticanju sazrijevanja i proliferacije astrocita i/ili oligodendrocita te usmjeravanju rasta aksona subplate neurona koji projiciraju u corpus callosum. The aim of this study was to describe the expression of the glycoprotein tenascin-C (TN-C) in the subplate zone (SP), in the period between gestation weeks (GW) 12 and 40, using the indirect immunohistochemistry method on postmortal brain tissue. The expression of TN-C starts in GW 16 in the deep SP and lasts up to GW 40. Its expression was not detected in the superficial portion of the SP. Apart from the SP, its expression is visible in the intermediate zone (IZ) and the cortical plate (CP). All three of the aforementioned zones show a fronto-occipital variation in TN-C expression. In GW 12 its expression was seen only in the IZ, and afterwards in all three zones in GW 16. In the frontal lobe TNC expression weakened by GW 20, and was either seen faintly, appearing sporadically, or was not detectable at all. It becomes clearly visible again in GW 25 and remains of weak intensity until the end of the gestation period. In central regions the expression is weak during the early and mid-fetal periods, but becomes moderate during the final period and is sustained until the end of gestation. Parietally the expression appears in the middle of the mid-fetal period and disappears by the late fetal period. The expression of TN-C did not correlate to the ingrowth of afferents from the thalamus and the basal forebrain. Its possible roles include autocrine stimulation of astrocyte and/or oligodendrocyte differentiation and proliferation, and axon guidance for subplate neurons projecting to the corpus callosum.