Right off the top of my head I can't think of the chapters and verses. What it comes down to is that the Catholic church still views the role of priest as a man's job. It's along the lines of the husband is to be the leader of his household as Jesus is the leader of the church. Jesus was male and the leader of the disciples. All of the original twelve disciples were men. They in turn taught men to be leaders in the individual church gatherings. As a side note, I believe this all to be a held over tradition from Judaism - which is the original religion followed by the disciples and some continued to follow many of the Jewish traditions, celebrations, and rituals.
Your question could also be asked to some of the other Christian denominations because there are others which also do not allow women to be preachers, elders, deacons, etc. In my opinion, as long as the person, male or female, knows the Bible, teaches what it teaches, and lives their lives by what they teach, they should be recognized and ordained as a priest or pastor.