INVESTIGATION OF DNA-SYNTHESIS IN EXPERIMENTALLY-INDUCED LONG-EVANS RAT MYELOSCHISIS BY THE BRDU ANTIBRDU TECHNIQUE/

The volume and DNA synthesis of the neuroepithelium in induced myelosc hisis in Long-Evans rats as shown by hematoxylin-eosin and BrdU/antiBr dU immunohistochemical staining patterns were examined at different st ages of embryonal development. On day 14 of gestation, control animals contained BrdU-incorporating cells mainly at the alar plate of the cl osed neural tube. On the same day, the everted neural plate of rats wi th myeloschisis showed active, diffuse uptake of BrdU in the cells of the matrix layer, although an increase in the volume of the everted ne ural plate was not yet identifiable. On day 21 of gestation, rats with myeloschisis showed a marked increase in the volume of the neuroepith elium compared with controls. Our investigations suggest that, in myel oschisis, more neuroepithelial cells than normal retain their capabili ty for DNA synthesis on day 14 of gestation, and the overgrowth of the neuroepithelium found on day 21 is possibly a secondary effect of fai lure of neural tube closure.