[Histologic and ultrastructural features of cell death both physiological and induced by two different teratogens in branchial arches of mouse embryo]. / Aspects histologiques et ultrastructuraux de la mort cellulaire programmée et induite par deux agents tératogènes dans les arcs viscéraux de l'embryon de souris.

ABSTRACT

AIM OF THE STUDY To observe and compare cell death process both physiological and associated with the administration of two different teratogens (irradiation and retinoic acid) inside cephalic mesectoderm. MATERIAL AND METHODS: Irradiated mice 2 Gy were administered to E 9 embryos. Retinoic acid 60 mg/kg were gave to E 8 or E 9 embryos. E 9 - 9.5 and E 10 embryos were removed. E 9 - E 9.5 and E 10 control specimens were collected. We used semi-thin sections and ultra-thin sections observed with transmission electron microscope. RESULTS: The major process is apoptosis, which is increased in experimental embryos compared to control specimens. However, autophagy was observed in retinoic acid-treated embryos, while necrosis can rarely occurs after irradiation. CONCLUSION: If the common process seems to be apoptosis, both teratological models differs owing to their respective secondary features. These differences should be explained by the specific pathogenesis of both teratological agents ligand-receptor reaction and Hox system disruption in retinoic acid administration, direct aggression against DNA and diffuse cell death process following irradiation. Furthermore, congenital malformations induced by these teratogens are quite different. This can be partially explained by a specific blow of different cellular subpopulations.