Sixteen white Wistar female rats were divided into two equal groups. Experimental group received per os 40 mg/kg b.w. of L-arginine, every other day for 2 weeks and were decapitated after 3 weeks of the experiment. Control rats received in the same manner 2 ml of distilled water and were decapitated after 3 weeks of the experiment. The renal lesions observed under electron microscope were of focal character and concerned only the experimental group. The tubules with necrotic cells were observed among normal tubules or single normal epithelial cells of the tubular wall. The boundaries between epithelial cells of the tubule wall were blurred. The mitochondria indicated abnormal structure. Numerous lysosomes and peroxysomes with dark, homogenous content were observed. The rough endoplasmic reticulum had widened channels and was focally completely destroyed. The nucleus of damaged cells was most commonly located in one of the cell poles; its shape was changed and visibly smaller than the nuclei of normal cells. Condensation and peripherally located chromatin were noticed. The lesions observed were characteristic for apoptotic cells.
