FIGURE 1.

Human brain organoids and their use in modeling the mechanisms of microcephaly. (A) Cartoonist representation of 3D human brain organoids. (A) Group of brain organoids. (B) Slicing off a 3D organoid. (C) An exemplary slice showing apicobasal progenitors in a ventricular zone Legends for the specific region or cell types are given. (D) Schematics explain possible structural abnormalities that could occur between healthy (left) and microcephaly (right) brain organoids. Microcephaly can be caused by genetic mutations (inherited microcephaly) or ZIKV infections (acquired microcephaly). In both cases, what appears to be shared is premature differentiation of NPCs leading to cortical thinning and overall size reduction. Note that control organoid displays NPCs whose division plane is mostly horizontally oriented to the lumen of the ventricular zone, a signature of symmetric expansion. In microcephaly organoids, the division planes of NPCs are mostly vertical. Legends for the specific region or cell types are given. These figure adapted from Gabriel et al. (2017).