Development of the Fetal Cerebral Cortex in the Second Trimester: Assessment with 7T Postmortem MR Imaging

Transverse T2-weighted 7T MR images of 12 (A, E), 16 (B, F), 20 (C, G), and 22 (D, H) weeks GA. Sagittal T2-weighted 7T MR images of 13 (I), 16 (J), 18 (K), and 20 (L) weeks GA. The lateral sulcus and the interhemispheric fissure can be distinguished at 12 weeks GA (A, E). At 16 weeks GA, more sulci can be observed (B, F), such as the central sulcus and the superior frontal sulcus. At 20–22 weeks GA, the sulci are more clearly delineated (E–H). On the sagittal images, development of the calcarine fissure, the parieto-occipital sulcus, the central sulcus, and the superior frontal sulcus can be clearly distinguished. The bar in each figure represents 1 cm; if, interhemisphaeric fissure; cas, callosal sulcus; cis, cingular sulcus; cf, calcarine fissure; pof, parieto-occipital sulcus; ots, occipitotemporal sulcus; las, lateral sulcus; sfs, superior frontal sulcus; its, inferior temporal sulcus; pcs, precentral sulcus; cns, central sulcus.

3D visualization model of the telencephalon, cerebellum, and brain stem of 12 (A), 16 (B), 20 (C), and 22 (D) weeks GA. Sulci on the brain surface are visible. The tiny lateral sulcus can be observed at 12 weeks GA (A), then it becomes wider and deeper (B–D). A cluster of shallow “sulcal roots” is delineated at 16 weeks GA (B), then the roots merge together and become deeper (C–D). ifs indicates inferior frontal sulcus; psts, posterior part of the superior temporal sulcus.

Quantitative measurements of fetal brain surface area and volume. The measurements increase linearly with GA. The surface area increases faster. Surface area is in square centimeters, and volume is in cubic centimeters. BA indicates brain surface area; BV, brain volume. The blue points represent the males, and the green represent the females.