Abstract

Myeloid body formation is an ultrastructural feature of gentamicin induced nephrotoxicity in human being and experimental animals. The origin of the myeloid body is not satisfactorily understood and morphological verification of the developing process of this structure is not fully accomplished. We injected 100 mg/kg/12 hour of gentamicin in 20 Spraque-Dawley rats and examined the ultrastructural feature of the proximal convoluted tubular cells of the kidney every 30 minutes in the first 4 hours, and in 5 hours, 6 hours, 12 hours, 24 hours and 48 hours after injection of gentamicin, with a TEM and a SEM. Myeloid bodies were noted as concentric layers of membranous structures of degenerated endoplasmic reticulum and mitochondria in the lysosome. The number and size of the myeloid body containing lysosomes were increased with time. We can deduce from this observation that injured cell organelles by diffusible gentamicin within the cells are autophagocytosed by lysosomes which were also injured by the drug from pinocytotic vesicles, and incompletely digested organellar remnants are retained in the lysosomes as myeloid bodies. So we think that the myeloid body formation is a result of an exaggerated and a pathologic autophagocytic process due to cell injury induced by gentamicin.

• Keywords: Gentamicin;Nephrotoxicity;Myeloid body;SEM;TEM