[Suppression of ontogenic development of the rat popliteal lymph node due to blockage of the afferent lymphatic vessels at early postnatal age].

We reported previously that surgical interruption of the afferent lymphatics to the popliteal node at the lowest edge of the popliteal fossa in young rats caused suppression of ontogenic development of the popliteal node. However, in that experiment we did not take into consideration the fact that, in the rat, the popliteal node sometimes receives minute afferent lymphatic channel(s) from the tail. In the present study, therefore, we interrupted the afferent lymphatic vessels at the lowest edge of the left popliteal fossa in Wistar rats at 7 days after birth in order to examine the effects of lymphatic drainage from the tail on the treated nodes, and sacrificed the animals at 2, 5, 10 and 18 weeks after the operation. A solution of 0.4% Evans blue was injected into the root of the tail on the left side 30 min before the animals were killed. Treated nodes receiving lymphatic channel(s) from the tail were stained with the dye and referred to as Eb(+)-treated nodes, whereas those without the channel(s) were unstained and referred to as Eb(-). At 7 days after birth, the normally developing popliteal node weighed 0.2 mg, and its parenchyma was composed of reticular cells with dispersed lymphoid cells. At 4 weeks after birth, each normal node weighed 2-3 mg; its parenchyma was comprised of two layers, an outer layer of peripheral cortex containing 30-40 lymph follicles and an inner discontinuous layer of deep cortex made up to 2-3 deep cortical units.(ABSTRACT TRUNCATED AT 250 WORDS)