This coincided with having been told by a medical commission which graded disability that they had been placed in the lowest grade, which meant that they would be kept for life in a retirement home (there were no homes for disabled people as the Soviet Union saw 'invalids' as flaws in the system) with no right to work or be independent in any way. Dasha fell into a depression and tried to hang herself when the pair were 18. Dasha fell in love with a fellow student, but Masha put a stop to the romance. The twins had by now developed very different personalities, with Masha being dominant, tomboyish and cheeky, and Dasha submissive, thoughtful and quiet. In 1968, their third leg was amputated in an effort to make them less noticeable to the Soviet public, who were not used to seeing disabled people. They studied here for four years in what they later recalled was the happiest time of their lives. As a result, the twins were transferred to a boarding school for children with motor-impairment in Novocherkassk, southern Russia, to continue their education. In 1964, news spread to Moscow that a girl with two heads was being kept in the institute. They were kept hidden from the public in a children's ward there for the following eight years.

In 1956 they were transferred to the Central Scientific Research Institute of Traumatology and Orthopedics (TSNIIPP) (Центральный научно-исследовательский институт протезирования и протезостроения) in Moscow where they were taught to walk and given an elementary education. Tubes were routinely inserted into their stomachs to monitor gastric juices and blood was taken from them three times a day. Their lung, heart and brain activity was constantly monitored by pneumograms, electrocardiograms and encephalograms. Experiments included packing one twin in ice to bring their temperature down to near-fatal levels while observing temperature changes in the other twin, burning them, starving them, depriving them of sleep, and electrocuting them in time with a metronome to test their reflexes. Masha and Dasha's case is now considered a prolonged case of medical torture. The twins were placed in the Academy of Medical Sciences Pediatric Institute, where a team of Anokhin's physiologists continued to carry out experiments on them for the following six years. In Autumn 1950, under Stalin's rule, Anokhin was exiled for two years for his anti-Soviet views on genetics (which taught Lysenkoism and Lamarckian evolution rather than Mendelian genetics and Darwinian evolution). The Soviet Academy of Medical Sciences produced a documentary film detailing the research. In reality, the twins had been taken to the Institute of Experimental Medicine in Moscow to be studied and experimented on under laboratory conditions. Scientists did not want her to keep custody of them, so she was later told by one of Anokhin's physiologists that they had died of pneumonia. A night nurse brought the twins to their mother and let her hold them. She agreed, but on the condition that she would keep custody and visit them regularly. When the twins were born, their mother was told they required full-time care from the State. They were born joined at the waist at a 180-degree angle with two heads, two torsos, four arms and one leg each, and a third, vestigial limb at their back that had some movement. The doctors told her she had delivered a severely disabled child ( урод) and she was not shown the babies. Masha and Dasha's mother, Yekaterina Krivoshlyapova, did not know she was having twins and spent two days and nights giving birth naturally. He began studying Masha and Dasha within days of their birth. He had put out an alert to all maternity hospitals in the USSR to be informed if any conjoined twins were born. Conjoined twins who shared a blood system but had separate nervous systems were ideal objects for research.

The Soviet physiologist Pyotr Anokhin was studying the separate roles of the nervous system and the blood system on the body's ability to adjust to conditions such as prolonged sleep deprivation, extreme hunger, and extreme temperature change. Their mother was told that her daughters had died soon after their birth. They were removed from their mother's custody at birth to be studied by Soviet physiologists. Maria and Daria ('Masha and Dasha') Krivoshlyapova (Мария и Дарья Кривошляповы, 3 January 1950 – 17 April 2003) were Ischiopagus tripus conjoined twins from Russia.

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