The effect of an organochlorine and an organophosphorus insecticide on the fine structure of flight muscle and the implications for the maintenance of contractility

Abstract

1. 1. DDT, either topically applied or injected, and topically applied parathion cause pronounced ultrastructural changes in the mitochondria and sarcoplasmic reticulum (SR) of cockroach flight muscle fibres. 2. 2. DDT application caused disintegration of the dense matrix of type A mitochondria, and vacuolation and loosening of cristae in type B mitochondria. 3. 3. Parathion induced a universal disintegration of the dense matrix in all mitochondria. 4. 4. The pronounced DDT-induced rearrangement of SR membranes resulted in the elaboration of myelin-like whorls or stacks, often confluent with rearranged mitochondrial membranes. 5. 5. Parathion application resulted in total disintegration of the SR tubular structure 6. 6. These insecticide-induced ultrastructural changes are discussed in terms of the maintenance of contractility and the operation of the contraction-relaxation cycle.