The formation of the neural tube in rat embryos, cultured in vitro, studied with teratogens.

With rat embryos cultured in vitro, two mechanisms are studied which are involved in the elevation and apposition of the neural walls: the mesoderm compartment and the "purse string" of the neurectoderm. The first is counteracted using hyaluronidase injected into the head-folds, the second using cytochalasin B or D, injected into the amniotic cavity. All teratogens cause malformations. Hyaluronidase produces inversion of the head-folds, and the cytochalasins cause eversion. Injection of both hyaluronidase and cytochalasin, however, results in a near to normal closure of the head-folds.