The impact of ethanol exposure during fetal development on the retina of chicken embryos

Abstract

It is common knowledge that excessive consumption of alcohol by pregnant women may lead to neonatal mortality, a delay in fetal development and serious malformations. In this study, we used the chicken-embryo model to demonstrate the ethanol teratogenic effect on the development of the retina. Forty-nine fertilized eggs were employed in our experiment. As a result, the chicken embryos were injected with varying amounts of ethanol in the air space (10%, 30%, and 50%). The eggs were kept in a humid incubator with a temperature of 37 °C and a humidity level of 60–65%. On the 20th day of incubation, the eggs were cracked and the chicks were examined with their length and body weight taken into account. These operations were followed by the resection of the ocular globes for a histological examination. The eyes were fixed with formalin at 10%. The right eye was sectioned at 5μm with a Leica microtome. Hematoxylin-Eosin staining was, then, applied on the slides, which were also observed under a microscope. The optic-microscopic observation of the ocular samples of each group has revealed that the in ovo ethanol exposure has caused retina changes, including the internal plexiform and the ganglion-cell layers. In treated groups the thickness of these two layers decreased in comparison with the control group. In conclusion, the current findings indicated that treating chicken embryos with ethanol at an early stage resulted in significant abnormalities and a lower embryo survival rate. Ethanol has harmful effects on the embryonic development including growth retardation and ocular abnormalities; this effect is dose-dependent.