During the journey of a sperm for feilization with an ovum, the process 'capacitation' takes place in:

Once ejaculated into the female, the spermatozoa move up the uterus to the isthmus of the uterine tubes, where they slow down and undergo capacitation. This fuher maturation process involves two components: increasing the motility of the spermatozoa and facilitating their preparation for the acrosome reaction. From the isthmuses the capacitated spermatozoa move rapidly to the tubal ampullas, where feilization takes place. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 23. Function of the Male Reproductive System. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.