The biophysical basis of MRI signal in the normal human prostate is uncertain, whereby the normal peripheral zone has high ADC values and returns high signal on T2-weighted imaging. In this study, we use MRI in combination with quantitative digital histopathology to offer an explanation. Paired scans were performed at 3T on a human prostate, prior to and following prostatectomy and changes in zonal morphology and MRI characteristics were measured. The peripheral zone collapsed and reduced in T2 signal intensity and ADC value ex-vivo. Digital histopathological analysis suggested the peripheral zone stores more ejaculatory fluid than the transition zone.