Prenatal Growth and Development of the Water Vole Arvicola amphibius (Rodentia, Arvicolinae)

The morphological and morphometric characteristics of water vole embryos are studied. Embryo implantation is observed on the fifth day of pregnancy. The morphological features of embryonic development at different stages of pregnancy are described, and equations for embryo body weight and length are derived. The results of multiple regression analysis have shown that the embryo weight is negatively correlated with the number of live embryos when considering the influence of gestational age. Our results complement the existing literature data on the biology of mammalian development and can be useful for establishing the equivalent stages of embryonic development in different species in comparative studies. The morphological features of development and the embryonic growth equations can be used to determine the gestational age and calendar dates of the beginning and end of the breeding season in natural populations.