Oviposition in the Lungless Salamander Onychodactylus japonicus Induced by Injection of Frog Pituitary and Commercial Gonadotropins

If a proper dose of gonadotropic substances was injected, oviposition occurred on the 3rd or 4th day after injection. Administration of 500 IU of Puberogen (hCG, Sankyo Co. Ltd., Tokyo) is practical for inducing oviposition. Injection of fresh anterior pituitaries of adult Rana catesbeiana showed a lethal effect as well as an oviposition-inducing effect, e. g., one half of the animals injected with one pituitary died on the 4th day or later after the treatment. No difference in the death rate was recognized between the sexes. The lethal effect of acetone-dried pituitaries was less than 1/10 that of the fresh pituitaries. Therefore, administration of acetone-dried pituitaries is also practical. Serotropin (PMS, Teikoku Hormone Mfg. Co. Ltd., Tokyo) showed a similar oviposition-inducing potency similar to that of Puberogen, but it is rather expensive for practical use. The number of eggs laid by one female of this species was 2-20, 11 on the average.