Goniomitosis in rats affected by mycoplasma or macrolides

Infection with Mycoplasm pulmonis caused a slight increase in the incidence of chromosome breaks in goniomitotic cells of the rat testis. No differences existed between healthy and infected rats in the frequency of mitotic divisions, measured as the number of metaphases per slide. The macrolide antibiotics erythromycin and tylosin are widely used as antimycoplasmal drugs. Erythromycin was given to healthy rats intramuscularly at a concentration of 20 mg/kg, and tylosin perorally in the drinking water at a concentration of 0.1%, both for 10 days. Neither drug induced an increase in the incidence of chromosome breaks in the spermatogonia. But both these macrolides caused a definite reduction in the therapy of cell division. With erythromycin, this effect had disappeared 18 days after the end of treatment.