Fig. 1. Timecourse of zebrafish brain ventricle formation. (A-K) Ventricles were visualized by microinjecting a fluorescent dye, Texas Red-dextran, into the hindbrain ventricle of anesthetized embryos. (A) Ventricle injection schematic: lateral view of 24 hpf embryo with microinjection needle at injection site of hindbrain ventricle. (B-K) Developmental profile of brain ventricle morphology at 18, 20, 22, 24, and 30 hpf following dye injection; (B-F) dorsal views; (G-K) lateral views; anterior to left. Heartbeat onset at 24 hpf (E), after brain ventricles have formed. (L-O) Cell morphology of hindbrain ventricle was visualized by confocal microscopy after overnight immersion in fluorescent molecule bodipy ceramide. (L) Diagram of lateral view of 18 hpf embryo, with horizontal plane used for confocal time-lapse imaging indicated by green line. (M-O) Confocal time-lapse imaging of hindbrain ventricle of living, anesthetized embryo, beginning at 19 hpf and ending at 20 hpf. Asterisks label hinge-points from which opening begins, and arrows point to locations of apparent adhesion that release as ventricle opens anterior to posterior. Asterisks: midbrain and hindbrain hinge-points. Scale bar: 50 µm. A, anterior; F, forebrain ventricle; H, hindbrain ventricle; M, midbrain ventricle; P, posterior.