https://youtu.be/mnJYho2mgDA
To visualize the beating heart and vasculature of a chick embryo (72 hours old), ink is injected into its yolk sac artery with a finely drawn glass capillary needle. A window is cut into an egg to expose the embryo and then placed under a stereo microscope (Zeiss Stemi 2000-C; 10x magnification). Video by By Anna Franz, Sir William Dunn School of Pathology, Oxford and MBL, Woods Hole.