Fig. 8. Ligation model. Ligation of the right vitelline artery of a 30 ss chick embryo in ovo. (A) Overview of an embryo 24 hours after ligation. Note venularization of the ligated vitelline artery (arrow). The unligated vitelline artery shows enhanced growth across the midline (arrowheads). (B-L) Still images of time-lapse videomicroscopy of another ligated embryo taken at the indicated time points. The future major venous branch can be seen in H (arrow). Note incorporation of an entire branch of the vitelline artery into this vein (arrows, H-L). Asterisks in I-L indicate another arterial segment that becomes venularized. Scale bars: 945 µm in A; 715 µm in B-L.