Place of publishing:
Development of sexual maturity and reproductive activity in Arvicola sapidus Miller, 1908, was studied. The sample analyzed consisted of 374 specimens (208 males and 166 females), captured in various localities in southern Navarre (Spain). Maturity and sexual activity of the males were evaluated both from the cytological analysis of testicular and epididymal tissues and by the testicular and vesicular size. Maturity and sexual activity of the females were determined as a function of the vulva condition, size and vascularization of the uterus, presence of embryos and placental scars, histological analysis of the ovary and development is related to age, season and size of both the individual and its reproductive organs. In the studied population there are males with spermatozoa present throughout the entire year.