Table 2.
Fifty-three-hour embryos
| Treatment | Survivors/treated (%) | Delay (%) | NTD
|
Total NTD (%) | ||
|---|---|---|---|---|---|---|
| Spinal (%) | Cranial (%) | Multiple (%) | ||||
| HcysTD | 167/187 (89%) | 29/167 (17%) | 5 (3%) | 18* (11%) | 23 (14%) | 46/167 (27%) |
| HcysTD plus FA | 15/22 (68%) | 6 (40%) | 4 (27%) | 1 (7%) | 3 (20%) | 8/15 (53%) |
Embryos were treated with 5 μmol of l-Hcys thiolactone (HcysTD) as in Fig. 1, and analyzed for the occurrence of neural tube closure defects. Embryos in the Delay column were at stages 10–12 rather than at stage 14, as predicted by the time of incubation (53 h). A second set of embryos was treated simultaneously with 5 μmol of l-homocysteine thiolactone to which was added 0.1 μg (100.0 ng) folic acid. The folic acid offered no protection from the dysmorphogenic effects of the Hcys. Some members of the HcysTD-treated group that showed cranial defects also showed a duplication or branching of the notochord just caudal to the cranial closure defect. FA, folic acid; NTD, neural tube defects.
Four of 18 showed duplication of the notochord.