Effects of environmental toxicants on development of a teleost embryo.

Embryos of the teleost Fundulus heteroclitus are shown to be useful model systems for monitoring the effects of xenobiotic compounds on development. Fourteen different substances were tested: malathion, aroclor, aldrin, diquat, parathion, pentachlorophenol, sevin, toxaphene, lindane, 2,4-D, DDT, paraquat, 2,4,5-T, and aminotriazole. Concentrations used for each of these was from 0.01 to 10.0 ppm in the incubation dishes. The variety of effects on development observed depended on the compound and its concentration. These effects included inhibition of gastrulation, abnormal axis formation, diminished pigmentation, slowed rate of development, reduced frequency of hatching, loss of neuromuscular control, and reduction or inhibition of heart beat. Possible modes of action of some of these compounds are discussed. It is also shown that embryogenesis is not always the most susceptible part of the organism's life cycle.