Effect of Thiourea on the Development of the Amphibian

Effects of Thiourea Upon the Development of Anuran Larvae

“…Hanaoka (1954) likewise demonstrated that the large tadpoles of Rana temporaria which were treated with 0.025% thiourea failed to develop beyond the premetamorphic stage. Gordon, Goldsmith and Charipper (1945) reported that the large tadpoles of Rana pipiens immersed in 0.033% thiourea continued to advance at metamorphosis but at signithe larvae of Rhacophorus schlegelii immersed in 0.0125% thiourea at the middle larval stage metamorphosed several days later than the controls.In a 0.025% solution, metamorphosis of the tadpoles was remarkably inhibited,but some of the tadpoles continued to advance gradually at metamorphosis for longer periods of time.…”

“…Beginning of metamorphic change was considerably retarded in E .Body size in each group on the 32nd day is shown in It is widely known that amphibian metamorphosis is inhibited by antithyroidal substances (Gordon, Goldsmith andCharipper, 1943,1945;Hughes and Astwood 1944;Gasche, 1946;Thomas, 1947;Lynn, 1948;Schindler,Schar and Staehelin, 1948;Delsol, 1952;Hanaoka, 1954;etc.). Gasche (1946) reported inhibition of metamorphosis in Xenopus laevis tadpoles which were kept in a 0.04% thiourea solution from the early stage of larval life.…”

“…It may be considered that the degree of metamorphosis-inhibiting effect of thiourea is dependent upon the stage of the initial treatment, concentration of thiourea, difference in species, and so on. As Gordon, Goldsmith and Charipper (1945) and Gasche (1946) 2. When the treatment was initiated at earlier tadpole stage and much concentrated solution of thiourea was used,the growth of tadpoles was much more significantly inhibited.When tadpoles were treated for longer periods of time, however,reversed was the case.…”

Mechanisms of tail resorption during anuran metamorphosis

“…This discovery is refined by the inhibition of metamorphosis via treatment with a thyroid hormone (TH) synthesis inhibitor and by acceleration via treatment with purified TH, thyroxine (3). These studies demonstrate that thyroid hormones are essential and sufficient to induce the drastic morphological changes during anuran metamorphosis, including tadpole tail resorption.…”

Sex Reversal in Female Tadpoles Induced by the Treatment With Methylmercaptoimidazole

“…Since Gordon et al(1943) (Iwasawa,1955a(Iwasawa, ,b,1958a)and on the precocious germ cell differentiation (Iwasawa,1957a) were remarkably thicker than those of controls.Histological activity of the gland was parallel with the height of the follicular epithelium.It may be said that the results described above are essentially similar to those of thiourea treatment previously reported (Iwasawa,1956a(Iwasawa, ,1957b). In Exp.2,as shown in Figure 2,the gonads of the treated animals are slightly smaller in size than those of controls.Histological examination on the gonads also revealed the slight retardation of sex differentiation in the treated animals.…”