Calibration of injection needle using a micrometer. To ensure a consist injection volume, use a micrometer to measure the diameter of the injection bubble volume. An injection bubble diameter of 100 μm is equivalent to 0.5 nl.

Brain and intravenous microinjection sites. A. Red arrow points to brain injection site in the right tectum and white box outlines the right tectum region of the larval brain at 3 dpf. B. 30 s after fluorescent dextran injection into the brain tectum (red arrow), the fluorescent tracer can be readily observed to disperse into the brain ventricles and into the spinal canal (red arrowheads). C. Red arrow points to the intravenous injection site at the caudal vein plexus located beneath the dorsal aorta (top red arrowhead) and near the urogenital opening (bottom red arrowhead). D. Full body image 30 s after intravenous injection shows fluorescent dextran signal throughout the entire body vasculature. Red arrowheads point to vasculature in the head and trunk made visible by fluorescent dextran. White dotted box, region shown in E. E. Immediately following intravenous injection, the heart (red circle) is filled with fluorescent dextran signal. Red arrowheads point to fluorescent signal in the gill vasculature.