"What, no, oh no, Jess its me , we are friends, this was just a fun thrill joke, please, oh please no, as from how you have changed in species and now of gender, your semen, it might be infectious and change me, my species. If i were to become as changed as you, we might both get stuck, unable to return back to being ourselves!" Mary pined and pleaded with Jess.
Indeed, Jess had changed, she feared becoming an animal, but the second vial reinforced her bodily changing, generating male organs.
As Mary hung there struggling, she kicking here legs, while she felt the pointy end to what had to be Jess, she more then a buck goat enthralled with having his cock sliding inside a friend.
As Mary struggled, the sensations coming from down low were rising up inside her sexual depths. Horrified, her urge to fight only made Jess delight with the sensations from becoming male, as then an animal, a buck goat.