Final answer:
Spermatozoa can survive in the uterine tubes for 3 to 5 days after ejaculation, which is essential for fertilization since this increases the chance that sperm will encounter and fertilize an oocyte.
Step-by-step explanation:
The transit and survival of spermatozoa in the female reproductive tract is critical for fertilization. After ejaculation, sperm face several challenges where many are neutralized by the acidic vaginal environment or hindered by cervical mucus. Yet, some manage to enter the uterus, and only a few thousand make it to the uterine tubes—the typical site for them to encounter the oocyte. The journey through the uterus usually takes from 30 minutes to 2 hours.
If the sperm do not immediately find an oocyte, they can survive in the uterine tubes for 3 to 5 days, increasing the period during which fertilization can occur. This timespan is crucial since intercourse a few days before ovulation may still result in fertilization, whereas intercourse more than a day after ovulation is less likely to do so because the oocyte is viable for only 24 hours post-ovulation.