Brain tissue fragments in the amniotic fluid of rats with neural tube defect

AIMS: Brain tissue nodules are occasionally seen in the lungs of neural tube defect (NTD) cases. We looked for brain tissue fragments in amniotic fluid of rats with NTD as it is the basis for the aspiration hypothesis. METHODS: Eighty-seven pregnant rats were randomly divided into experimental (n=58) and control (n=29) groups. Experimental rats received 100,000 U of vitamin A in 1 mL of corn oil on gestational days 8, 9 and 10, while control rats received corn oil. On gestational days 15, 18, 19, 20 and 21, amniotic fluid was drawn from three control animals and five experimental animals and analysed. RESULTS: NTD was found in 22.75% of experimental fetuses and in no control fetuses. Brain tissue fragment number and volume fraction increased between gestational days 18 and 20, falling on day 21. CONCLUSIONS: Excessive doses of vitamin A induce a high rate of early fetal death and development of NTD. Brain tissue fragments in the amniotic fluid reflect the evolution from exencephaly to anencephaly and could support the aspiration hypothesis. However, as it is a late event in the rat, this model may not reproduce the brain tissue nodules in the lung.