Effects of 5-bromodeoxyuridine on development of Mauthner's neuron and neural retina of Xenopus laevis embryos

Bromodeoxyuridine (BrUdR) injected into Xenopus embryos at stages before, during or after the last period of DNA synthesis in Mauthner's neurons had no serious effect on differentiation of Maunthner's neurons. However, the BrUdR caused widespread cell degeneration in the central nervous system. The action of BrUdR on retinal neuronal differentiation depended on dose and stage of injection. At all doses (0.005-0.9 μg per injection), and all stages (22-29), the main effect was retinal cell degeneration. The drug produced complete absence of differentiated retinal neurons only when given at early stages (22-24) and at the highest doses (0.5-0.9 μg) that enable the embryo to survive to stage 44. At stages 22-24 at lower doses (0.005 or 0.05 μg per injection) and at stages 26-29 at all doses, some retinal neurons differentiated, although retinal cell degeneration was the main effect. In these two system BrUdR did not selectively inhibit neuronal differentiation.