embryonic toxico-pathological effects of origanum vulgare: evaluation of the gross and histopathological lesions using a chick embryo model

Background & objective: toxico-pathological effects of herbal plants have always been a major concern, but little information is provided on the toxico-pathological effects of origanum on the fetus. due to ethical rules and regulations, no drug experiment on the human fetus is permitted; hence, the chick embryo model is used as an ideal opportunity to study the adverse effects of drugs. this study aims to assess the histopathological effects of the various doses of origanum vulgare (o. vulgare) using the chick embryo model. materials & methods: ross chicken eggs were subjected into four experimental groups (n=7); phosphate buffered saline-injected group and origanum-injected groups that were treated with o. vulgare leaf-extract at doses of 25, 50, and 100 mg per kg egg-weight, respectively. after injecting the embryos with the extracts, re-incubation was performed and allowed to develop until day 18, when embryos were evaluated for pathological lesions. results: treated embryos were normal in the origanum-injected groups and no defect was noticed on the body features. the microscopic lesions including congestion and edema were made in the brain, liver, kidney, heart, and lung in a dose-dependent manner. conclusion: it can be concluded that o. vulgare at a concentration higher than 25 mg per kg is toxic for chick embryo in a dose-dependent manner; therefore, more attention should be given to the toxicity of o. vulgare in the period of fetal development.