This book explains the effects of the organochlorine pesticide endosulfan on two embryonic stages (days 6&12) of the chick. It provides experimental methods such as eggs incubation and treatment, histological procedures for skeleton staining and tissue preparations. The book also illustrates the morphological and skeletal descriptions of normal and abnormal chick embryos with emphases on the incidence of external and skeletal malformations following endosulfan treatments. Besides, a complete description of the histological and histopathological characteristics of the developing kidney (mesonephric and metanephric) types of both embryonic days. The book contains 30 photographs (describing the morphology and skeleton of the normal and abnormal embryos) and 28 microphotographs (describing the histological and histopathological characteristics of the developing kidney).