Most of the 'drainage pipes' in your skin are actually made of immune cells, not blood vessel cells like we’ve been told for years.
March 20, 2026
Original Paper
A Csf1r lineage gives rise to dermal lymphatic endothelial cells
bioRxiv · 10.64898/2026.03.17.712362
The Takeaway
For decades, biology textbooks have taught that the lymphatic system grows exclusively out of existing veins. This study reveals that 60% of the lymphatic cells in the skin actually come from a completely different family tree of immune cells, fundamentally changing our understanding of how the body's 'second circulatory system' is constructed.
From the abstract
Lymphatic vessels are formed during embryonic and postnatal development to facilitate interstitial fluid clearance and immune regulation after birth. Their organ-specific heterogeneity in organisation and function is preceded by heterogenous origins of lymphatic endothelial cells (LECs), the main building blocks of lymphatic vessels. In the dermis, a subset of LECs was reported to arise from blood capillaries, which themselves differentiate, in part, from paraxial mesoderm. However, it is not kn