T-lymphocyte and B-lymphocyte dichotomy in anuran amphibians: I. T-lymphocyte proportions, distribution and ontogeny, as measured by E-rosetting, nylon wool adherence, postmetamorphic thymectomy, and non-specific esterase staining.

We used sheep erythrocyte (SRBC) E-rosetting, nylon wool fractionation thymectomy and nonspecific esterase staining to assess T-lymphocyte characteristics in Rana pipiens during various developmental stages. T-lymphocytes appear in the spleens of premetamorphic tadpoles. We found significant levels of lymphocytes classifiable as T-cells in the peripheral blood of adults, but fewer numbers of T-cells in the thymus, jugular bodies, spleen, pronephros, mesonephros, liver and bone marrow. In addition, thymectomized Xenopus laevis showed a sharp decrease in T-cells as evidenced by E-rosetting, ANAE stain and nylon wool fractionation. The presence of T-lymphocytes in anuran amphibians and the existence of a receptor for SRBC on a population of these cells, suggest conservation of T-cells during evolution.