The aim of this study was to evaluate the effect of methanolic extract of plants from the north of Mexico,
on testicular morphology and spermatic quality in Wistar rats. Methanolic extracts were orally administered to 4 experimental groups (n=6) of rat for 30 days; a control group not treated with plant extract was included. All animals were sacrificed 24 h after the last dose. Samples of testicles were collected, fixed, processed by histological technique and embedded in paraffin blocks. Histological sections were stained with H&E, Masson’s trichrome and histochemical PAS reaction with diastase. Results of the groups treated with methanolic extract of Tagetes lucida, Cynodon dactylon, Lippia graveolens HBK, and Opuntia ficus-indica testicle samples demonstrated epithelial detachment and cell fragmentation, an apparent decrease in the diameter of seminiferous tubules, with large empty spaces between them and areas with fragmentation of basal membrane. Sperm quality analysis (concentration, motility and viability) showed a significant decrease of these spermatic parameters in all treated groups. In conclusion, this paper demonstrated for the first time that methanolic extracts from plants of the north of Mexico, have toxic effect on testicle and affects spermatic parameters of Wistar rats.