Developmental malformations of human tongue and associated syndromes (review)

The development of the tongue begins as known, in the floor of the primitive oral cavity, when the human embryo is four weeks old.More specifically, the tongue develops from the region of the first three or four branchial arches during the period that the external face develops. Malformations of the tongue, are structural defects, present at birth and happening during embryogenesis. The most common malformations are:1. Aglossia2. Microglossia, which is always combined with other defects and syndromes, like Moëbius syndrome3. Macroglossia, which is commonly associated with cretinism, Down’s syndrome, Hunter’s syndrome, Sanfilippo syndrome and other types of mental retardation4. Accesory tongue5. Long tongue6. Cleft or Bifid tongue, condition very usual in patients with the orodigitofacial syndrome7. Glossitis Rhombica Mediana, a developmental malformation?8. Lingual thyroid.Malformations are extensively analysed and discussed.Le développement de la langue commence au niveau du plancher de la cavité orale primitive lorsque l’embryon humain est âgé de 4 semaines.Plus précisément, la langue se développe dans la région des trois ou quatre premiers arcs branchiaux durant la période du développement de la face externe. Les malformations de la langue correspondent à des défauts de structure présents à la naissance et survenant au cours de l’embryogenèse. Les malformations les plus communes sont:1. Aglossie2. Microglossie, qui est souvent combinée à d’autres anomalies ou syndromes, tel le syndrome de Moebius3. Macroglossie, qui est communément associée au crétinisme, au syndrome de Down, au syndrome de Hunter, au syndrome de Sanfilippo et à d’autres types de retard mental4. Langue accessoire5. Langue longue6. Langue bifide, condition très usuelle chez des patients présentant le syndrome orodigitofacial7. Glossite rhomboïde médiane (?)8. Thyroïde linguale.Les malformations sont analysées et discutées

Craniofacial abnormalities induced by retinoic acid: a preliminary histological and scanning electron microscopic (SEM) study

Exogenous retinoic acid has been found to be teratogenic in animals and man. Craniofacial defects induced by retinoic acid have stimulated considerable research interest. The present report deals with scanning electron microscopical observations of the craniofacial region concurrent with histological examination of craniofacial dysmorphism induced in rat embryos following maternal treatment treated with varying dosages of all-trans-retinoic acid (tretinoin). Two groups of pregnant rats were treated with rat embryos exposed to retinoic acid suspended in corn oil (100 mg/kg b.w. on gestational day 11.5 and 50 mg/kg b.w. on gestational day 10, 11 and 12 respectively). A third group was treated with corn oil (vehicle) while a fourth group remained untreated. A wide spectrum of congenital abnormalities, including exophthalmos, microphthalmia and anophthalmia, maxillo-mandibular dysostosis, micrognathia of both maxilla and mandible, cleft palate, sub-development of ear lobe, preauricular tags and macroglossia, were observed in the offspring of retinoic acid treated animals. The abnormalities were both time and dosage dependent, and characteristic of Treacher Collins syndrome when retinoic-acid was administered on gestational day 11.5. In contrast, when retinoic acid was administered were on,gestational days 10-12, the defects were similar to those seen in the first and second pharyngeal arch syndrome, as well as in the oculo-auriculo-vertebral spectrum. Whereas our data support the hypothesis that all-trans retinoic-acid disturbs growth and differentiation of several embryonic cell types essential for normal craniofacial development, its mechanism of action remains unclear