quotes Chazal (Gemara in Nidda) as follows:
איש מזריע בו לובן שממנו גידים ועצמות ... אשא מזרעת אודם שממנו עור בשר ודם
The man provides the white from which the bones and sinews grow ... the woman provides the red from which the skin, meat, and blood come
The Ramban then quotes the Greek philosophers who disagree with Chazal
ועל דעת חכמי הפלוספי היונים כל גוף העובר מדם האשה אין בו לאיש אלא ... שהוא נותן צורה
And the Greek philosphers say that the all of the body of the child comes from the blood of the women the only thing that comes from the man is the tzura (whatever that means)
The Ramban clearly and unequivocally records the opinion of the Greek philosophers who argue on a scientific opinion of Chazal.
This is the same Ramban who is the foundation of much of Jewish thought today and who was a great mystic/kabbalist.
