Original Sin is Episode 6-5 of Second Opinion. It's a story-only episode.
Story
Dr. Miller approaches a recovering Derek, and leads him into the heart of the research facility. It is there where Derek comes face-to-face with Adam's preserved body. Dr. Miller mentions that their regenerative treatment research originated from Adam - they believe the way his body has been kept free of putrefaction holds the secret to regenerating lost tissue. Derek is outraged at this, but Dr. Miller suggests his opinions are best expressed at the upcoming conference.