Images were obtained with a Nikon SMZ1500 microscope or a Nikon inverted A1r spectral confocal microscope. Confocal z-stack image acquisition in multiple fluorescent channels was used to examine the entire dorsal aorta in the AGM . Immunofluorescence double staining was performed as described previously,58 (link) with anti-p-akt S473 (1:25; cat. no. 9271; Cell Signaling) and AlexaFluor 594–conjugated anti-rabbit secondary antibody (1:1000; cat. no. A11012; Life Technologies).