Objective:To observe the impact of acupuncture on morphological changes of retinal cells after intraperitoneal injection of N-methyl-N-nitrosourea(MNU) in the rat.Methods: Twenty 50-day-old female SD rats were randomized into control(n=4)

model(n=8)

and acupuncture(n=8) groups.Retinal degeneration model was established by intraperitoneal injection of MNU(50 mg/kg) in the rats of the later two groups.Bilateral "Xinming"(behind the ear

the mid-point of the folding region inferior to the ear's lower angle)

and "Jingming"(BL 1) were punctured once daily

continuously for 7 days.Following finishing the experiments

the rat's eyeballs were taken out to be immersed in 4% paraformaldehyde

embedded in paraffin

sectioned

stained with hematoxylin and eosin stain

and observed by using light microscope and transmission electron microscope(TEM).Results: Compared with normal control group

the outer nuclear layer(ONL) thickness and the total thickness of the retina in model group showed thinning significantly(P<0.01)

and the cells' arrangement was in disorder;when compared with model group

the ONL thickness and the total thickness in acupuncture group were markedly bigger(P<0.01) and the cellular arrangement was relatively well-arranged.Results of TEM showed smaller(withered) cellular body

condensed nuclear chromatin

swelling of the mitochondria with severer vacuole

etc in model group

while in acupuncture group

the apoptosis of the photoreceptor cells was apparent but the injured degree was much lighter than that of model group.Conclusion: Acupuncture can protect retinal photoreceptor cells from MNU-induced injury in rats.