Two Cases of Oviducal Prolapse Found in the Lungless Salamander Onychodactylus japonicus

Abstract

Fifteen males and 15 females of Onychodactylus japonicus collected in the breeding season were placed in a dark box containing 2cm of water, and were kept at a constant temperature of 10°C. No food was given. These conditions are suitable for the induction of spawning in this species. After 19 and 20 days, a remarkable prolapse of the right oviduct occurred in two females which had not yet ovulated. It is conceivable that the oviducal prolapse was caused directly by the acceleration of oviducal movement. As one of the predispositions to oviducal prolapse, the peculiarity of the nature of the egg sac in this species may be considered.