Figure 6: Rod-shaped nuclei in the primo vessel. (a) Phase contrast microscope image of a primo vessel that was extracted from a lymph duct. (b) Fluorescence microscopic image of the boxed area in (a). The boxed area was magnified, and the part with rod-shaped nuclei was the primo vessel. The round-shaped nuclei were aggregated lymphocytes. (c–f) Confocal laser scanning microscope images of the circled area in (b). These panels were consecutive optical sections from top to bottom separated by 2 μm in each step. The same rod-shaped nucleus appeared (panel (c)), looked long (panels (d) and (e)), and then nearly disappeared (panel (f)), which implies that this particular endothelial nucleus was inside the primo vessel and, therefore, had not aggregated from outside.