title: Immunofluorescent detection and localization of thyroxine in blood of Rana catesbeiana from early larval through metamorphic stages.
abstract: Indirect immunofluorescent staining was used to detect and localize thyroxine (T4) in blood smears from individual Rana catesbeiana tadpoles in almost every stage of larval development. Earlier radioimmunoassays revealed a surge of T4 in the blood plasma during metamorphic stages, but plasma T4 concentrations in earlier stages were either very low or below the minimal detectable limits of the assays. With the present immunofluorescent method, T4 was found in plasma of tadpoles throughout the entire larval period from early limb bud stages to the end of metamorphosis. Moreover, T4 was also found in association with cytoplasm and nuclei of red blood cells, particularly nuclei of the new population of adult red cells differentiating during metamorphic stages. In conclusion, thyroid hormone is present in both blood plasma and erythrocytes of R. catesbeiana from early through late stages of larval development.
mesh_terms: D000818:Animals; D005455:Fluorescent Antibody Technique; D007814:Larva; D008675:Metamorphosis, Biological; D011892:Rana catesbeiana / Q000097:blood* / Q000502:physiology; D013974:Thyroxine / Q000097:blood*; D014018:Tissue Distribution
chemical_list: D013974:Thyroxine