Endosulfan Impacts on the Developing Chick Embryos: Morphological, Morphometric and Skeletal Changes

摘要

This study aims to explore the effects of the organochlorine pesticide Endosulfan (35% EC) on the developing chick embryos. After 24 h of eggs incubation, a single dose of 7 or 14 or 21 mg Endosulfan/egg was administered through the egg air space at once. The eggs were opened on embryonic days 6 and 12 and the embryos were evaluated for viability, wet body weights and various morphological, morphometric and skeletal changes. Skeletons of 12-day-old embryos were stained by alizarin red S and Alcian blue using a whole mount double cartilage and bone staining technique. Comparing the three doses with control and with each others, the high dose treatment resulted in statistically significant more embryonic deaths, while the mid-dose caused statistically more malformed embryos. On both embryonic days, the treated embryos exhibited dose-related growth retardation, as reflected by significant reductions of embryonic wet body weight, anterior-posterior head and crown-rump lengths as well as generalized edema and hematomas formations. Also, on embryonic day 12 significant reductions of beak length, eye diameters and measurements of wing and hind-limb parts were recorded. Abnormal survivors showed high percentages of limb deformities (as limb paralysis, clinodactyly, flexion and shortness of limbs or digits), microphthalmia, microtia and omphalocele. The skeleton of treated embryos showed anomalies and incomplete chondrification and/or ossification of some skull parts (interorbital septum, frontals, parietals, palatines and external auditory apertures), cervicals, scapulae, ribs, sacrals and caudals. These findings suggest that Endosulfan exhibits embryotoxic and teratogenic effects on the developing chick embryos in terms of growth retardation, external and skeletal malformations.