| Abstract: | The effect of blockage of the afferent lymphatic vessels on the development of popliteal lymph nodes in the rat was studied. The afferent lymphatic vessels to each popliteal node were surgically interrupted at the lowest edge of the popliteal fossa at 3, 7 or 28 days after birth and the popliteal nodes were obtained from treated animals at 4, 8 or 16 weeks after the operation. At 7 days after birth, each popliteal node was small and weighed 0.2 mg. Its parenchyma consisted of reticular cells and a small number of dispersed lymphoid elements. Four weeks after birth, each node weighed 4-5 mg, and its parenchyma comprised two layers, an outer continuous layer of peripheral cortex containing 40-50 lymph follicles and an inner discontinuous layer of deep cortex made up of 4-5 deep cortical units. At 10-12 weeks after birth, each node weighed about 10 mg and showed full structural development; the peripheral cortex contained 100-130 lymph follicles and the deep cortex consisted of 4-6 well developed units. The popliteal node was drained by 4-6 afferent lymphatic vessels, which opened into the subcapsular sinus of the node. Each lymphatic opening was topographically associated with a respective deep cortical unit, as previously described by Bélisle and Sainte-Marie (1982). In animals treated at 3 or 7 days after birth, the development of the popliteal nodes was considerably inhibited. Four weeks after surgery, each node showed 10-30 lymph follicles in the peripheral cortex and 1-3 small units in the deep cortex. Sixteen weeks after surgery, the node weighed about 4 mg and its cortex exhibited about 50 lymph follicles in the peripheral cortex and only 2 units in the deep cortex. The popliteal nodes of the treated animals generally received 2 afferent lymphatic vessels. In animals treated at 4 weeks after birth, the popliteal nodes showed no gain in weight for following 16 weeks. Four weeks after surgery, each node usually had 4-5 deep cortical units and 50-60 lymph follicles. Thereafter, some units and their overlaying peripheral cortex underwent atrophy, while others persisted. Sixteen weeks after surgery, the popliteal node showed only 2 deep cortical units and 50-60 lymph follicles, and was drained by 2 afferent lymphatic vessels. Surgical interruption of the afferent lymphatic vessels to the popliteal node at the lowest edge of the popliteal fossa did not obliterate all the draining lymphatic vessels , but reduced the number of vessels opening into the node.(ABSTRACT TRUNCATED AT 400 WORDS) |
