Ridley Scott's audio commentaries during the scene between Lambert and the Alien :
"I mean we didn't know how she died but the implication of this was a kind of sexuality to this androgynous male/female who could give birth itself but could also impregnate so it's like er, there are insects like that so we're based on, you know, a little bit of good old mother nature and was that some dreadful ending, was that some terrible, you know, invasion of her body, a rape, and therefore would there be a (an alien) version of the Cartwright character ? There'll certainly what happens, there will be more humanoïd alien now on board of this craft now so that's what she is going to destroy."
Up to now, I though there was only one xenomorph on board of the Nostromo but without selfdestruction, there would be two of them chasing Ripley alone
