Groups of sexually immature Japanese quail females, kept in a reduced photoperiod, received either daily intraperitoneal injections of 40 micrograms estradiol-17 beta for 26 days or were fed diets containing 0, 10, 40, 80 or 160 ppm chlordecone for the same duration. Estradiol-17 beta induced rapid cellular hypertrophy, cytodifferentiation, tubular gland formation, organelle proliferation and secretory granule formation in different cells of the quail oviduct. Higher chlordecone doses mimicked these estradiol-17 beta actions, but in addition induced atypical cell and organelle morphology, such as protruding or swollen cell apices, increased mitochondrial volume densities and diameters and disorganized Golgi apparati. The possible effects of these chlordecone-induced atypical cell alterations on avian reproduction are discussed.