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. Author manuscript; available in PMC: 2023 Jun 1.
Published in final edited form as: Nature. 2022 May 25;606(7914):570–575. doi: 10.1038/s41586-022-04766-2

Fig. 3: The functional specialization of AF vessels is linked to their cellular origins.

Fig. 3:

a-b’, AF LVC forms patent connections with systemic circulation at stage III. Distribution of intravascularly injected Rhodamine dextran (MW=2000 kDa) in stage II (a-a’) and III (b-b’) AFs, shown along with LVC (mrc1a:EGFP+) and BVC (kdrl:BFP+). Blood-borne tracer (red) is seen in the lumen of mrc1a+ vessels in stage III but not in stage II AFs. c-c’, Lymphatic transdifferentiation occurs before the LVC connects to blood flow. sox17GFP expression is detected in the LVC (arrowheads) before the intravascularly injected Qdot705 (cyan) enter the LVC compartment (c’). All vessels in c are labeled with fli1a:dsRed. (d) Confocal image (also shown in Fig. 2j), depicting the connection between the AF and the trunk blood vasculature mediated through sox17GFP+ vessels. e-i, Lack of lymphatics induces blood vessel-derived vascularization of the AF. Stage II AF of flt4−/− lacks lyve1b:dsRed+ LVC (f), that is present in WT siblings (e, red). kdrl:GFP+ BVC is detected in both (e,f, green). Arrowheads in f point to the connections with cloacal vessels and PCV. Stage III WT AF is primarily vascularized by LVC-derivatives (g, lyve1b:dsRed), whereas only BVC-derived vessels are detected in AFs of flt4−/− (h, kdrl:GFP). i, Status of BVC-derived vessels (kdrl:GFP), 22 days post NTR-Mtz mediated ablation of LVC in Tg(prox1a:Gal4;UAS:NTR-mCherry) animals. Arrows point to small patches of prox1a+ LVC cells that escaped ablation. j-j’, flt4−/− mature AF display erythrocyte pooling (j’, arrowheads, n=10) as opposed to WT siblings. k, Comparison of radial morphology between WT and flt4−/− animals, revealing major defects in the MR. q, Radials have been magnified and color coded to reveal the three segments – PR, MR and DR, of the WT (left) and flt4−/− (right). Scale bars, 30 μm (a,b,c), 50 μm (d,e,f,g,h,j), 100 μm (i), 300 μm (k). NTR, Nitroreductase, Mtz, Metronidazole, μCT, Micro-computed tomography, PR, Proximal radial, MR, Medial Radial, DR, Distal Radial.