Very often Catholics are challenged by non-Catholic Christians regarding not only the high esteem we hold for the Blessed Mother but also for the Church's doctrines of her Immaculate Conception, life-long virginity, and her Assumption into Heaven. Along with our traditional explanations for these doctrines, we can now add to the discussion the ever increasing knowledge of human cell biology.
Chances are the word "microchimerism" is not part of your vocabulary. However, this medical knowledge can give us some insight into what the Church has been teaching for centuries. Microchimerism is the term used to identify the exchange of body cells between a child in the womb and the child's mother during her pregnancy. Noted during the 1990's it has been discovered that these cells can remain with the mother throughout her life. We now accept on faith that Mary was taken up into Heaven at the completion of her earthly life, identified as the doctrine of the Assumption celebrated on August 15th each year. But if any cells of Jesus remained in her body, which science now tells us is a direct possibility, it was imperative that those cells not be destroyed. The Bible tells us that the body of the holy one will not undergo corruption (Acts 13:35).
Microchimerism also has ramifications to our belief that Mary was not only sinless but a life-long virgin, since her body would have remained a physical temple of Jesus long after His birth. With a part of Jesus within her, purity and chastity were absolute necessities. Mary was immaculately conceived to prepare her for her role as mother of our Savior, just as the Arc of the Covenant was constructed with only the finest materials. She had vowed and remained a virgin, suggestive of the Arc that was not allowed to be touched without significant penalty (ref. 2 Samuel), and with a part of Jesus' very being potentially still within her, she was afforded the dignity of being assumed into Heaven when her earthly life had ended.
The Catholic Church has always taught the hidden wisdom of God, in this instance through our Marian doctrines. Interesting that medical science continues to uncover evidence to support what has always been our firmly held beliefs.