C4B and cyclic hematopoiesis: Ablation of the Bmp signaling (in BmpR1a/b double knockout mice) was reported to prevent CH induction (Fernandes et al., 2007), while mice with downregulated Bmp signaling still develop a CH-like structure at the telencephalic dorsal midline (Chizhikov et al., 2019; Hébert et al., 2002).