الفهرس 
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Abstract
Background: Vitamin A and its derivatives (Retinoids) are essential for both normal embryonic development and maintenance of differentiation. Retinoids is a well-known teratogen when administered to embryos
Aim: to investigate the structural changes induced by prenatal administration of vitamin A on the developing spinal cord of albino rats.
Material and Methods: forty pregnant albino rats were exposed to variable doses of vitamin A (retinyl palmitate) on gd 10. The pregnant albino rats were divided into three groups: group I (control): rats received sesame oil by oral gavage daily, till date of delivery. group II (minimum therapeutic dose): rats were given retinyl palmitate 50 mg/kg daily. group III (maximum therapeutic dose): rats were given retinyl palmitate 100 mg/kg daily. The viable offspring of all groups were evaluated for changes in developing spinal cord at PND1, 10 and 20. At the end of the experiment, rats offspring were sacrificed, the spinal cord were dissected out, and subjected to histological examination followed by computer image analysis.
Results: PDN1 neonates of mothers received minimum dose of vitamin A (subgroup II) revealed few immature irregular dorsal horn neurons with relatively decreased cellular density in anterior horn neurons. Meanwhile, the PDN1 neonates of mothers received daily maximum therapeutic dose of vitamin A (subgroup III) exhibited dark, pyknotic nuclei and packed dorsal horn cells while anterior horn cells were shrunken and karyolitic nuclei. PDN20 neonates of subgroup II revealed shrunken and pyknotic dorsal horn neurons with immature and distorted anterior horn neurons. PDN20 neonates of subgroup III exhibited dark, karolytic dorsal horn cells while the majority of the anterior horn cells appeared to be shrunken and deeply stained with pyknotic nuclei.
Conclusion: minimum and maximum doses of vitamin A in pregnant rats attributed to morphological changes in spinal cord of their young neonates and in long term follow up which was more obvious in maximum dose than low intake. Therefore, it might be assumed that neither minimum nor maximum dose could be used as a safe drug for their serious side effects on spinal cord morphology and consequently its functions.