Detection of membrane Testosterone receptors in prostat epithelial cells by flow cytometry. A: Cells were isolated from specimens of radical prostatectomy, as described in Material and Methods, stained for 10 min with 10-7 M of testosterone-BSA-FITC (blue curve, 2) or BSA-FITC (yellow curve, 1), and the fluorescence was measured in a Coulter-Epics apparatus. The specific fluorescence is the difference of the two peaks (bar B). B: Time course of the specific testosterone-BSA-FITC fluorescence (bar A in Figure 1A). Results of a typical experiment (case number 35 in Table 1).