Figure 1. The lymphatic vessels of the zebrafish heart facilitate regeneration after injury.

(A) Schematic drawing showing the ventricle (pale orange) and outflow chamber (pale gray) of an adult zebrafish heart. The outer surface of the outflow chamber contains many large lymphatic vessels (green), and the ventricle is spanned by a few coronary arteries (red) that guide lymphatic vessels during growth. (B) Four days after traumatic cryoinjury, fibrotic tissue has accumulated in the wounded tissue, and this area becomes densely vascularized during the healing process. (C) At 60 days post-injury, fibrotic tissue has been replaced with a regenerated cardiac muscle (enclosed within the dashed line). Newly formed lymphatic vessels facilitate this regeneration by removing excessive fluid and inflammatory cells from the damaged tissue.