Histological observations on rat popliteal lymph nodes after blockage of their afferent lymphatics.

: Afferent lymphatic vessels to the popliteal lymph node in the rat were blocked, and the node was histologically examined 2-35 weeks later. After the operation, the node was reduced in size and its lymphoid structures, such as germinal centers, lymph follicles and deep cortex units, were decreased in size and number. At 16 weeks, the lymphoid organization of the node reached a minimal level, but the node still exhibited reduced numbers of lymphoid structures. The lymphoid parenchyma of the node, although reduced in size, showed no noticeable change in cellular density during the period of observation. The changes observed in the popliteal node following blockage of the afferent lymphatics were interpreted as resulting from a reduced supply via the afferent lymph of antigens and other factors on which the development and persistence of the lymph node structures are believed to depend.