Surgeons in California have successfully separated conjoined twin girls, in a highly complex operation which lasted more than 12 hours.
Regina (left) and Renata are said to be doing well
The 10-month-old girls, Regina and Renata Salinas Fierros, were joined from the lower chest to the pelvis and shared a number of organs.
A medical team of 80 began operating on the pair early on Wednesday in the operation at a hospital in Los Angeles.
The twins are expected to remain in hospital for several weeks.
Born of Mexican parents, the girls' liver, intestines and pelvis were among those organs which needed dividing.
"To see the girls beginning to wake up and move and respond is great excitement for us all," lead surgeon Dr James Stein told a news conference.
Regina is the weaker of the pair, with only one kidney.
The scene in the operating theatre was described as orderly calm, as one of the twins was moved to an adjacent room after separation.
Doctors continued work through the night reconstructing the twins' chest walls and pelvis regions, and sewing up surgical wounds.
Surgical director Henri Ford told AP the girls "looked very healthy and quite good".
An 80-strong medical team took part in the operation
"Everything has been going impeccably as one could possibly imagine," he said.
Dr Ford said the twins' parents were "relaxed and pleased with the progress".
Lead surgeon James Stein and fellow senior medic Dominic Femino both participated in a successful operation to separate conjoined twins in 2003.
If twins have separate sets of organs, the chances for survival tend to be greater than if the organs are shared.
The two girls have US citizenship after being born in Los Angeles while their parents were visiting the country on a tourist visa.
Several hundred conjoined twins are born every year worldwide.
Conjoined twins originate from a single fertilised egg, so they are always identical and of the same sex.
The overall survival rate of conjoined twins is somewhere between 5% and 25%.
Over the past 500 years, historical records show about 600 surviving sets of conjoined twins with more than 70% of the surviving pairs being female.