Old Testament verses other than Genesis 3:15 speak of the "seed" of a woman. How, then, does it indicate a virgin birth?

I am researching prophecies about the virgin birth of Jesus in the Old Testament and am currently trying to find answers on specific issues. **Genesis 16:10; 24:60; 4:25; Leviticus 22:13; 1 Samuel 2:20-21.** The above verses talk about women and their "seed". How do these verses and prophecies agree with the prophecy of Genesis 3:15 if this verse refers to the virgin birth? And how does the "seed of the woman" in Genesis 3:15 differ from the 'seed of' the women mentioned in all the other Old Testament verses? Can anyone enlighten me as to how these verses fit together?