A New Screening Model Using F1(AWE * WE) Japanese Quail Embryo for Evaluating Sex Reversal Effects

Abstract

F1(AWE × WE) strain of Japanese quail (Corturnix japonica) is produced from a mating between male AWE (albino plumage color) and female WE (wild plumage color) strains of Japanese quail. Male and female offspring exhibit wild and albino plumage colors, respectively, ruled by a criss-cross inheritance. F1(AWE × WE) eggs received 17 beta-estradiol (E2) or methyltestosterone (MT) at 0, 20, 200, 2000, and 20000 ng/egg just before incubation. At 16 days of incubation, embryos were subjected to a complete necropsy and their gonads were grossly observed and examined histopathologically. Viabilities of the embryos at 16 days of incubation were not significantly different between the control and all E2 groups and between the control and the MT 20, 200 and 2000 ng groups, whereas viability of the MT 20000 ng group was significantly lower than that of the control group. Grossly, genetic sex confirmed by plumage colors coincided completely with sex phenotype of the gonads in all embryos of the control and treated groups. Histopathologically, E2 exposure induced a dose-dependent feminization such as ovotestis of the left testis. No abnormalities were detected in any male embryos of all the MT groups. E2 and MT exposures induced no noticeable changes in the ovaries of any embryos. The present study suggests that the sex reversal test using F1(AWE × WE) Japanese quail embryos may be a rapid and cost-effective tool to evaluate screening feminization effects of the estrogenic endocrine disrupters.