Ultrastructural Changes in the Neurulation of Early Chick Embryos Treated with Diphenylhydantoin

ABSTRACT

Teratogenic effects of a diphenylhydantoin on the neurulation of the explanted early chick embryos were studied using the punched-out filter paper explantation technique. The 6th to 9th Hamburger and Hamilton staged chick embryos were explanted and cultured in the Ham's F-10 media treated with 15 microgram/ml, 30 microgram/ml, 60 microgram/ml, 90 microgram/ml, 120 microgram/ml of diphenylhydantoin in the CO2 incubator for 6-9 hours. The morphological chracteristics and the ultrastructural changes of the neuroepithelium of early chick embryos were compared with the control and experimental group using the stereomicroscope and the electron microscope. Of th 40 chick embryos cultured in the Ham's F-10 media without drug, 37 embryos(92.5%) developed normally and 3 embryos(7.5%) developed abnormally in 94 embryos(61.4%). The frequent anomalous features of the embryos were deformities of the neural folds in the cranial regions, failure of neural tube closure, dispersion of somites and developmental arrest. The scanning electron microscopic findings of neuropithelial cells of abnormally developed embryos were diminished surface blebs and microvilli, flattened and smooth cellular surfaces, and irregular size of cells. The transmission electron microscopic findings of neuroepithelial cells of abnormally developed embryos showed no significant changes of the development of intracellular organelles except the smooth cellular surface and mild underdevelopment of microfilaments.