In the present study, we developed a novel method to analyze the calcium (Ca² ) signal in living slices of mouse caput epididymides by applying calcium imaging on Fura-2-loaded vibratome slices. The data revealed that in epithelial cells of mouse caput epididymides, ATP induces a rapid Ca² signal that is sustained after 60 sec. Preincubating the sections in Ca² -free medium in the presence of EGTA did not affect the amplitude of the ATP-induced Ca² signal, indicating the presence of P2Y type purinergic receptors and phospholipase C activity. Furthermore, ATP induced a similar Ca² signal in the different subregions of caput epididymides. The P2X type ion-gated purinergic receptors could also be responsible for the ATP-induced Ca² signal because immunohistochemical and reverse transcriptase-polymerase chain reaction analyses showed that P2X1, P2X2, P2X4, P2X7, P2Y1, and P2Y2 receptors were expressed in the epididymis. We propose that P2X and P2Y receptor expression is vital for the normal function of epididymal epithelium and sperm maturation. Furthermore, the method we developed allows us to analyze the activity of various G protein-coupled receptors in intact epithelial cells of mouse epididymides, and other reproductive tissues as well.