Inhibition of nuclear migration in the absence of microtubules in the chick embryo

Interkinetic nuclear migration was studied in cells of the forming neural tube of cultured chick embryos aged from 1 to 7 pairs of somites. In specimens that were first exposed to 2°C for 3 h, then treated with 4 × 10 −3 M monoiodoacetamide and finally transferred to new media to be reincubated for 1−2·5 h, it was found that microtubules were absent and nuclear movements blocked. These findings point to microtubules as essential structures for interkinetic nuclear migration. Their relation to the problem of neurulation is discussed.