DEVELOPMENTAL ARREST IN LEPTODACTYLUS-FUSCUS TADPOLES (ANURA, LEPTODACTYLIDAE) .1. DESCRIPTIVE

Eggs of the neotropical frog Leptodactylus fuscus (Anura: Leptodactyli dae) are laid in foamy masses in burrows close to sites of temporary p ools. After about two days, tadpoles hatch into the foam, but after tw o days further development, if no rain has fallen, the tadpoles enter a period of developmental arrest, maintained until rain falls and the nest is inundated. Results reported here document the developmental st atus of the arrested tadpoles, and compare this with tadpoles that ent er water immediately. Arrest involves a gradual slowing and eventual c essation of cell proliferation, a slowing of hatching gland degenerati on, a cessation of limb bud morphogenesis and slowing of yolk utilizat ion from intestinal lining cells. Arrest is not simply the result of l ack of food, since the intestinal lining contains abundant yolk partic les when it begins. The period of developmental arrest is not unlimite d: around 20 days after egg deposition, the resultant tadpoles undergo progressive weight loss and eventually die; death occurred on average 27.5 days after egg deposition,under laboratory conditions.