Effects of low concentrations of ethanol on the embryonic development of Bufo arenarum

Abstract

1. The effects of low concentrations of ethanol on embryos of Bufo arenarum were studied. 2. Embryos maintained continuously (from stage 3 on) in 0.84–3.34 μM ethanol showed concentration dependent effects: delay in the development rate and on eclosion, loss of equilibrium, arhythmic contractions, swimming in atypical positions and high death rate. At lower concentrations the anomalies were concentration independent. 3. Embryos treated continuously with 0.002 and 0.21 μM ethanol until stages 19, 20 and 21 showed an important and selective increase in their Na content. 4. When the embryos were incubated discontinuously in 0.002 and 0.21 μM ethanol, from stage 3 to stages 12–13 and then transferred to Holtfreter solution, only a few of the above mentioned anomalies were observed; they were transient and the embryos recovered rapidly. 5. Treated embryos did not exhibit ultrastructural changes in their ectodermal cells.