engleski

In vivo MR imaging of transient subplate zone in the human fetal telencephalon

MR imaging of the developing human cortex (Kostovic et al, Cerebral Cortex, 12:536, 2002) offers an exciting possibility for in vivo (in utero) visualization of synapse-rich fetal subplate zone which serves as a , , waiting compartment“ for growing thalamocortical afferents. We analyzed appearance, regional development and resolution of the subplate zone in the human fetal brain on a 1, 5 Tesla device during strictly medically indicated diagnostic MR pelvic examination in pregnant women. The youngest fetus examined (11 postovulatory weeks, PW) displays trilaminar organization of the cerebral wall: ventricular-subventricular zone (VZ-SVZ), intermediate zone (IZ) and cortical plate (CP), while the pre-subplate zone (Kostovic & Rakic, J Comp Neurol 297:441, 1990) was too thin to be visualized by MRI. The formation of subplate zone (13-15. PW) can be recognized by MRI at 13 PW as a band of intermediate, transitional, T2 signal intensity between low intensity CP and high intensity IZ. During midfetal period (15-20 PW) subplate zone is characterized by the highest T2 signal intensity and prominent regional variations, from well developed in lateral neocortex, narrowing in depth of calcarine fissure and poorly developed in limbic cortex. Between 21-23 PW signal intensity increased in the superficial zone, presumably due to the accumulation of thalamocortical afferents. Between 24-32 PW there is gradual decrease of T2 signal intensity of the superficial SP. Resolution of SP as discernible architectonic compartment begins after 34 PW during formation of cortical gyri. In conclusion, we demonstrated that specific MRI signal properties of transient fetal zones enable the in vivo and in utero visualization of all major phases in the developmental history of the subplate zone. This opens new vistas for in utero study of developing fetal cortical circuitry and connectivity.

MRI

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