Reversible ultrastructural changes in the rhabdom of the locust eye are induced by long term light deprivation

Summary Quantitative electron microscopic analysis of the compound eyes of locusts (Schistocerca gregaria) subjected to long term light deprivation showed that disorganization of rhabdomal microvillus structure and disruption of rhabdomere fusion were significantly more prevalent in deprived animals than in controls. These structural changes accompanied a reduction in sensitivity to photic stimulation in the deprived eyes. The disorganization of microvillus structure was reversible after 14 days recovery in light while the disruption of rhabdomere fusion was irreversible. Deprivation also resulted in an irreversible increase in number of ommatidia bearing fewer than normal retinula cells. These results are consistent with disruption by light deprivation of some aspect of normal photoreceptor membrane synthesis or degradation.We thank Ms. Irene Kwan for her excellent technical assistance, Dr. H. Silverman for useful discussions through all stages of this study, and Drs. H. Injeyan and S. Tobe for supplying the hatchling locusts. This work was supported by Ontario Graduate Fellowships to J.W.B. and a National Research Council of Canada operating grant to H.L.A.