This field shows a longitudinal section of the vessel at the level of a valvule with its two leaflets. These two thin membranes are lined with an endothelium (arrows). In the lumen of the vessel on the right, the lymph (*) is free of cells. On the left, the lumen of the vessel contains numerous lymphocytes (L).

Obviously, the valve prevents the retrograde flow of these lymphocytes along the vessel. The connective tissue of the lateral wall is indicated (+).

Stain: H–­­E
Magnification: ×750