Cobalt (Co) is an essential trace element for mammals required for the synthesis of vitamin B12. When cobalt was applied chronically it tends to accumulate in different organs and tissues that can induce pathological alterations. We focused our present study on the comparative effects of chronic exposure to cobalt chloride (CoCl2·6H2O) or cobalt EDTA (Co-EDTA) on testis and sperm count in mice of different ages. Both compounds were given in drinking water water with doses per day of 75 mg/ kg or 125 mg/ kg, respectively. Treated animals were sacrificed at different time intervals (on days 18, 25, 45 and 60). The most obvious changes in testis morphology - depletion and retardations in germ cell development, disorganization of seminiferous epithelium and SCO (Sertoli-cell-only) tubules were observed on the studies of 45 and 60 days respectively. In early puberty, testis weight was reduced in similar extend (with 25%) after high doses of both Co compounds whereas in early maturity and adulthood this parameter was reduced significantly and more severe after exposure to high dose CoCl2 as compared to Co-EDTA, probably due to the stability of the complex Co-EDTA and its weaker absorption. Concerning gonado-somatic index and sperm count in mature animals we found similar tendency of more adverse effects with high dose of CoCl2. As a result of our work and data in literature we can conclude that the effects of chronic exposure to cobalt depend of the type of the compound used, dose, level, time duration as well as on the age of the animals under experiment. Cobalt could be considered as a possible risk factor for male fertility and health.
Key words: Cobalt chloride, Cobalt-EDTA, in vivo model, mouse testis, sperm coun
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