The lymphatic system controls fluid homeostasis and the clearance of macromolecules from interstitial compartments. In mammals brain lymphatics were only recently discovered, with significant implications for physiology and disease. We examined zebrafish for the presence of brain lymphatics and found loosely connected endothelial cells with lymphatic molecular signature covering parts of the brain without forming endothelial tubular structures. These brain lymphatic endothelial cells (BLECs) derive from venous endothelium, are distinct from macrophages, and are sensitive to loss of Vegfc. BLECs endocytose macromolecules in a selective manner, which can be blocked by injection of mannose receptor ligands. This first report on brain lymphatic endothelial cells in a vertebrate embryo identifies cells with unique features, including the uptake of macromolecules at a single cell level. Future studies will address whether this represents an uptake mechanism that is conserved in mammals and how these cells affect functions of the embryonic and adult brain.
- Stefan Schulte-Merker
- Max van Lessen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: Experimental procedures were conducted under project licence awarded to J.R. from the UK Home Office (Permit Number: 70/7612), according to the UK Animals (Scientific Procedures) Act 1986.
- Holger Gerhardt, Max Delbrück Centre for Molecular Medicine, Germany
© 2017, van Lessen et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.