Final answer:
In a vasectomy, sperm remain in the seminiferous tubules of the testis.
Step-by-step explanation:
In a vasectomy, a small section of the vas deferens is removed, which interrupts the path taken by sperm through the ductus deferens. If sperm do not exit through the vas, they remain in the regions of the testis where sperm are produced, specifically in the seminiferous tubules.