Comparative effect of the isomers of dimethylmyleran on spermatogenesis in the rat

Both meso- and racemic forms of dimethylmyleran are powerful antispermatogenic agents which cause a rapid depletion in the number of type A spermatogonia. A block on their proliferation causes a progressive depopulation of maturing germ cells in the seminiferous epithelium. Each isomer produces maximal reduction of Type A by 2 weeks and their recovery thereafter leads to restoration of the germ cells. Histological analysis of cell changes in the testis infers that Type A at Stage VII of the cycle of the seminiferous epithelium is susceptible to the action of the meso and +/- isomer, but the mixture interferes with Type A at Stages VII-XIV. Stem cell Type A survive treatment seemingly in normal number. During repopulation, the yield of Intermediate Type spermatogonia from Type A was relatively low for several weeks, after the use of the meso isomer, indicating the persistence of damage to the latter. An insufficient recovery period did not permit complete spermatid restoration.