Antispermatogenic effect of Achillea millefolium L. in mice.

The effect of an ethanolic extract (200 mg/kg/day, intraperitoneally, for 20 days) and a hydroalcoholic extract (300 mg/kg/day, orally, for 30 days) of Achillea millefolium L. (yarrow) flowers on the spermatogenesis of Swiss mice was studied by evaluating morphologic characteristics with the light and electron microscopes. The alterations observed were exfoliation of immature germ cells, germ cell necrosis, and seminiferous tubule vacuolization. Animals treated with the extracts had an increased number of metaphases in the germ epithelium that might be due to cytotoxic substances or substances stimulating cell proliferation.