Introduction: The aim of this study was to investigate the neurotoxic effects of prenatal morphine exposure on the development of cerebellar cortical layers (CCL) in the mouse embryo.

Methods: Female pregnant mice were orally administered 0.1 mg/ml morphine solution on the 17th day of gestation. Pregnant mice were killed afterwards and their fetuses were taken out and were evaluated for growth and cerebellar development. Quantitative computer-assisted morphometric study was done on cortical layers of cerebellum in the mouse embryos.

Results: Morphine exposure caused a significant reduction in fetal weight and crown-rump length in the morphine group. Morphometric examination revealed that the thickness of CCL, especially that of the external granular layer (EGL), was decreased in the morphine-exposed emberyos. In addition, neuronal counting showed that cell proliferation in the EGL and internal granular layer (IGL) was suppressed after morphine administration and that the migration of neurons from the neuroepithelial layer to the cortex was decelerated.

Conclusion: Morphine is a mitosis inhibitor and causes migratory disturbances of neurons at various stages of neuronal differentiation during cerebellar cortical development.

Hakim Research Journal 2007 10(2): 43- 49.