ABSTRACT
Retinoic acid is a vitamin-A derived compoundthat plays an important role in craniofacialdevelopment. However, numerousstudies have shown that exogenously administeredretinoic acid analogues have teratogeniceffects both in humans and in experimentalanimals. This paper presents the results of astudy where exogenous administration ofretinoic acid analogues to pregnant Wistarrats resulted in major craniofacial malformationsof most of the foetuses. Seven groups ofpregnant rats were exposed to a variety ofretinoic acid analogues, administered in differentdoses on different gestational days. Afurther control group was not exposed to thesecompounds. All the rats were impregnatedand sacrificed on the same gestational days(GD 0 and GD 18 respectively). Followingexamination of the 34 foetuses obtained fromthe retinoic acid-treated litters, 5 were chosenfor histological investigation to describe themajor, external craniofacial malformationsresulting from exposure to the teratogens.These malformations included exophthalmos,anophthalmos, exencephaly, craniofacial asymmetryand facial tags. Also reported here arethe incidences of teratomas and absorptions inthese litters. Previously, we have reported theincidence of cleft lip and palate in rats subjectedto an identical experimental regimen. Ourdata provide further evidence that retinoicacid analogues, all-trans-retinoic acid in particular,disturb normal craniofacial developmentin such a way that a spectrum ofcraniofacial malformations can be induced byembryonic exposure to these compounds (AU)
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