Final answer:
A nulliparous cervix belongs to a woman who has never been pregnant, while a multiparous cervix belongs to a woman who has given birth at least once. The cervix is crucial for protecting the uterus, aiding in fertilization, and changing during the stages of childbirth to allow the baby and placenta to pass through.
Step-by-step explanation:
The difference between a nulliparous and a multiparous cervix has to do with childbirth history. A nulliparous woman has never given birth (A), while a multiparous woman has given birth at least once (D). The cervix plays crucial roles in both fertilization and childbirth. It acts as a barrier that protects the uterus from foreign substances, and during fertilization, it secretes mucus that can help sperm travel to meet the egg. During childbirth, the cervix undergoes significant changes. In stage one of labor, the cervix thins (effaces) and dilates to allow the baby to pass through. In stage two, the baby is expelled from the uterus. Finally, during the third stage, the placenta passes through the now-dilated cervix following the birth of the baby.