Teratogenesis: The stage-dependent susceptibility of amphibian embryos to noxious agents

HERKOVITS J.; CASTAÑAGA, L.; SANDOVAL M.T.; ARONZON C.M.; C.S. PÉREZ-COLL

Simposio; Third International Symposium on Recent Advances in Environmental Health Research; 2006

Living organisms at developmental stages are very susceptible to physico-chemical stressors. As teratogenic agents produce usually mutagenic and carcinogenic effects, malformations are very relevant end points for adverse effects of single physico-chemical agents or complex mixtures, including environmental samples. By focusing on the stage-dependent susceptibility to noxious agents, in this study, the most susceptible developmental stages will be reported for UV-B irradiation, H2O2,lead, cadmium,naringenin, and an organometalic fungicide (funguicygon) as examples of exposure to different physico-chemical agents. Although certain malformations such as delayed development, axial incurvations, reduced body size, microcephaly, hydropesy; epithelial ridges, wavy tails, etc. could result from the exposure to different physico-chemical agents, the percentage of affected embryos could be different in each case and signature like features could be identified in certain cases. As a general pattern, the stage-dependent susceptibility to noxious agents point out: i) a very high resistance of the embryo (for both lethal and teratogenic effects) at early developmental stages (blastula-gastrula and even neurula); ii) a very high susceptibility at early organogenic stages (from neuromuscular activity to gill circulation stages) and iii) by the end of the embryonic development (from opercular folds to complete operculum) a gradually increasing resistance of the embryo to noxious agents. Thus, the exposure to environmental stressors during the organogenic stages seems to reflect the worst exposure condition scenarios, at least in amphibian embryos and for lethal and teratogenic endpoints.