ABSTRACT
Analytical experiments in animals have been possible due to the relative ease with which cell suspensions of lymphocytes can be manipulated. Chronic lymph drainage techniques and cell labeling methods have been particularly significant. In addition, the phenotypic description of different populations of lymphocytes has underscored the complexity of lymphocyte traffic and its source of wonderment to those interested in biology. Studies of lymphocyte migration in sheep involve the intravenous injection of labeled lymphocytes and analysis of their subsequent appearance in lymph or various tissues. The initial lymphatics or terminal lymphatic capillaries exist as blind-ended tubes or saccules in the interstitium. They have a close topographical relationship to blood capillaries and smaller venules. The cellular content of afferent lymph is usually lower than that of efferent lymph.
