Effects of oral morphine consumption during pregnancy on retina development of the Wistar rat embryo

  Introduction: Visual system is composed from different parts with different embryonic origins. In the present study, the effect of oral morphine consumption on retina development of the Wistar rat embryo was investigated.   Material and Methods: 40 female Wistar rats (250-300 g) were used. After mating, the embryonic zero day (E0) was determined and then the pregnant females were divided randomly into experimental or control groups. Controls received tap water whereas experiments received morphine (0.05 mg/ml) in their waters. On the E17, pregnant females were killed and embryos were removed and kept in formalin 10% for 30 days. Then, heads of the embryos were dissected and processed by routine procedures. Sagittal sections of 5um were stained with haematoxylin–eosin and examined by using a light microscope and the Motic soft ware.   Results: The retinal diameter was reduced in the experimental group. In addition, the granular and neural layers were fully developed in the control group, but they showed delayed developments in the experimental group. At last, there were empty pores between cells in the experimental group. Moreover, the plasma corticosterone levels were increased in the experimental group.   Conclusion: These results indicated that oral morphine consumption during pregnancy may induce defects in retina development in the rat embryo. This may be related to an increased in the plasma corticosterone levels.