Effect of avermectin on the ultrastructural characteristics of loach embryos

The ultrastructure of loach (Misgurnus fossilis L.) embryo cells at the stages of the first and tenth blastomere divisions in the presence of avermectin B (a compound that belongs to the class of macrocyclic lactones, avermectins) in an incubation medium at concentrations of 0.01, 0.1, and 1.0 μg/ml was studied. It was found that the effect of this compound led to ultrastructural changes in cell organelles, such as hypertrophy of the granular and agranular endoplasmic reticulum and disorganization of the mitochondria and the embryo plasma membrane. Avermectin activity causes dose-dependent destructive changes in organelles; such changes are the consequences of the destruction of metabolic and regulatory processes, caused by the inhibitory influence of avermectin on the processes of active transport of Na⁺, K⁺ and Ca²⁺ ions. The data obtained in this study show that avermectin is characterized by high embryotoxicity.