Hussaina and Hassana after the successful surgeryBLK Super-specialty Hospital 
The Iranian twins, who were law graduates, died while undergoing a surgery to separate their brains in July 2003. Though doctors could successfully separate the 29-year-old twins through a surgery that lasted 53 hours, none of the twins survived.Reuters 
Lori and Reba Schappell (now known as George) from Pennsylvania are joined together at the side of their heads, facing in opposite directions. In 2007, George announced that he was wrongly identified as a female at birth due to a condition known as gender identity disorder. Lori and George, at 51, are still leading life as conjoined twins and had revealed earlier that they do not want to get separated. "We're happy as we are. Why should we risk our lives just to conform to what society wants," the twins told BBC in 2004. "If we're separated the chances are one or both of us will die. Even if the operation is successful, we won't suddenly become normal, we'll be severely physically disabled."Reuters 
Four-year-old conjoined twins, Vani (L) and Veena, sit inside a hospital in the southern Indian city of Hyderabad May 8, 2007. Vani and Veena (9) were abandoned by parents shortly after birth, as they couldn't afford to bear their expenses. Since the last six years, the twins are under the care of Niloufer Hospital in HyderabadReuters 
Conjoined twins Sabah (L) and Farah attend a news conference in New Delhi in 2005.Reuters 
A team of 18 doctors at the Children's Medical Center of Dallas separated the two-year-old Egyptian twins in October 12, 2003.Reuters 
Four-Day-old conjoined twins rest in an intensive care bed at Guatemala City's Roosvelt Hospital. The twins were born to a 15 year-old mother named Wendy Sosa at the Roosvelt Hospital in Guatemala, Central America in July 16, 2002. According to the doctors, the safe separation of the twins was doubtful, as they were sharing the same heart, an occurrence that happens only one in 900,000 cases.Reuters
They came to this world physically joined to each other, but celebrated their first birthday separately.
A team of specialists at a Delhi hospital has successfully separated a pair of Nigerian twins, who were born joined at the buttocks, last month.
The girls, Hussaina and Hassana from Kano, were born with a condition known as pygopagus, where they shared their lower spinal cords, lower gastrointestinal tract and genitor-urinary tracts, with a common anus and genitalia.
As the doctors in Nigeria had little hope of saving both babies, they referred them to specialists at the BLK Super Speciality Hospital in Delhi.
A team of specialists under the supervision of Paediatric Surgeon Dr Prashant Jain conducted two life-changing surgeries to separate the babies. On 25 May, plastic surgeons inserted tissue expanders or silicon bags under the babies' skin on the buttocks. The silicon bags were inflated with saline, weekly, for two months. This helped to expand the skin and creation of tissue cover for the surgery.
At the end of the second surgery that lasted nearly 13 hours on 12 August, the specialists successfully separated the girls. Through another reconstruction surgery, the babies received separate genitalia and anal openings.
The girls celebrated their first birthday on 28 August.
Conjoined twins have been a much-talked about subject among medical enthusiasts around the whole world. According to health experts at the University of Maryland Medical Center, Baltimore in the US, such births are rare. One out of every 2, 00,000 live births have very few chances of survival - between five percent and 25 percent.
The whole process of twinning starts from the mother's womb, during the early stages of pregnancy. Conjoined twins are formed when a woman releases a single egg that fails to separate completely after fertilisation. Though the embryo starts splitting into two, the process stops in the middle and the partial separation results in conjoined twins.
Mary and Eliza Chulkhurst, commonly known as the Biddenden Maids who were born in England in the year 1100 and Eng and Chang Bunker, commonly called Siamese Twins, who were born in Thailand in 1811 are some of the famous conjoined twins in the history of medical science.
