An alien abduction is the kidnapping of a human by an alien species, typically for experimentation or examination. One who is abducted is said to be an abductee. Abductees are often returned with metallic tags inside their nasal cavities or inside their teeth, usually unknown to them. — (Pilot)
Dana Scully was one of numerous women abducted so that human ova could be extracted for use in a project developing an alien/human hybrid. The ova samples were tended to by Kurt Crawford clones at the Lombard Research Facility. — (Memento Mori)
Billy Miles was also used by aliens to abduct his high school friends. The aliens placed a tag-like device in his nose and would call him to abduct his friends and take them to the woods where a light would appear and take them to the testing place. Billy Miles claimed that the tests didn't work and they wanted everything destroyed and they said they were leaving. Many abductees where often taken and returned only to be abducted again some other time. — (Pilot)
Max Fenig was abducted many times and returned not knowing why he would wake up in strange places. — (Fallen Angel)
Duane Barry also was said to have been adbucted and used for experimental testing which drove Barry mentally unstable. Mulder believed that Barry was an abductee but Scully says he was suffering from a psychological illness causing hallucinations. This was until Barry attacked Scully in her home and abducted her only to be taken to the field where most abductees disappear. Once Mulder found Barry, he claimed that Scully was taken just like the others. — (Duane Barry, Ascension)
Samantha Mulder was first abducted from the Mulder house as Fox Mulder watched she was used in the cloning program. Her DNA was used to make alien human hybrid clones. — (Colony, End Game, Herrenvolk)
In 2000, (Oregon, Bellefleur) Agent Fox Mulder along with several other persons were abducted by alien colonists (TXF: "Requiem"), then returned in 2001 infected with a specially modified strain (super soldier form) of the alien virus. (TXF: "This is Not Happening", "DeadAlive"). These abductions are different from the earlier: collective abductions, which happen before the final alien invasion. (TXF: "Patient X"). Bellefleur was probably one of these places, which are called "lighthouses". The alien colonists acted without the human allies this time.