Neither the charges nor their names were released. They are cooperating in the investigation.
The seven entered their pleas in closed courtrooms and their names were withheld, but defense attorneys said that among those cooperating was the director of a funeral home that took parts from the body of "Masterpiece Theatre" host Alistair Cooke, who died in 2004.
The four original defendants in the case pleaded not guilty on Wednesday to enterprise corruption, body stealing and other charges in the new indictment. If convicted, they face up to 25 years in prison. All remain free on bail.
Prosecutors allege Michael Mastromarino, owner of Biomedical Tissue Services of Fort Lee, N.J., and three other men secretly removed skin, bone and other parts from up to 1,000 bodies from funeral homes, without the permission of families. They have accused the former oral surgeon of making millions of dollars by selling the stolen tissue to biomedical companies that supply material for common procedures including dental implants and hip replacements.