Zebrafish are an excellent model for studying the development and function of blood and lymphatic vessels. Research in zebrafish has even led to treatments for lymphatic disorders in people. This image, taken using a powerful microscope that uses lasers to illuminate the fish, shows blood vessels (magenta) and lymphatic vessels (green) in the eye and head of an anesthetized, 6-week-old, transgenic zebrafish.
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Credit: Daniel Castranova, National Institute of Child Health and Human Development, NIH