(CNN)The microscopic remains of hundreds of people executed by the Nazi regime and then experimented on by a collaborating doctor were buried on Monday.
Anatomy professor Hermann Stieve collected the corpses of people killed at Ploetzensee prison in Berlin throughout the Nazi period, before dissecting and studying their remains.
Decades later, tiny fragments of the victims' body tissue were discovered on microscopic slides at the doctor's estate and matched with the records of people killed at the prison. They were finally buried in a ceremony in Berlin on Monday afternoon.
The victims, mostly young women, were among thousands of people executed at Ploetzensee prison during the Third Reich.
"Stieve helped the Nazi justice system to deny these people a grave," Andreas Winkelmann of the Brandenburg Medical School, who identified the victims, told CNN. "He was not a member of the Nazi Party but he was not a resistance fighter either ... he benefited from a murderous Nazi system."
Stieve's main area of study was the female reproductive system, and most of the victims whose bodies he collected had been arrested for supposed political crimes.
"These were women imprisoned by the Nazi justice system. It could be for high treason, it could be for plundering after air raids ... or if you said something bad about Hitler, you could end up in jail or be executed," Winkelmann explained.
The professor was the director of the Berlin Institute of Anatomy from 1935 until his death, from a sudden stroke, in 1952. His slides were found in 2016 by family members, among various items from his career.
"Only when they looked at them closer and saw that there were names on some of them, they thought this was something that should be looked into," Winkelmann said. He went on to identify those names as belonging to people killed at Ploetzensee.
The tiny tissue samples lie on glass slides and measure about a hundredth of a millimeter in thickness and approximately a square centimeter in area.
The burial of the slides at Berlin's Dorotheenstadt cemetery, which was arranged in part by the Charité University Hospital, will "help restore some of their dignity to the victims," the hospital's CEO Karl Max Einhäupl said in a statement.
"You would not usually bury microscopic slides because the tissues are so small," Winkelmann added. "In this case, it is a special group of victims and they were denied a grave at the time, so the relatives didn't have a place to commemorate them."
Tens of thousands of political prisoners, including suspected resistance fighters, Communists and trade unionists, were incarcerated or executed by the Nazi regime before and during the Second World War, and Ploetzensee became notorious as a center of capital punishment during the era.