Assay of Thyroid-stimulating Hormone, Thyroid and Thyroid-like Substances on Xenopus Tadpoles

Abstract

IN 1941, Landgrebe and Purser¹ showed that larvæ of Xenopus lævis can be obtained in the laboratory all the year round, and suggested that they could be used for assay of thyroid and thyroid stimulating hormone. In 1945², Deanesly and Parkes published a method for assay of thyroid-like activities by oral administration, using these tadpoles at an early stage. Such animals, however, vary a great deal in sensitivity and are too small for satisfactory injection and operative surgery. In the past few years, the anatomy, feeding mechanism, growth, food requirements, development and metamorphosis of the larvæ have been thoroughly investigated. Methods for routine thyroidectomy and injection of extracts have been worked out using larger tadpoles. Methods of husbandry have been devised which reduce individual variation to a minimum, and produce large metamorphically retarded larvæ suitable for assay work (c. 400 mgm. with length of hind leg c. 0.3 cm.).