Craniopagus twins conjoined twins develop inutero remains unclear. Embryologists have traditionally attributed identical twinning as "splitting or fission" of either the inner cell mass of pleuripotential cells or early embryonic disc at 13–14 days of gestation just before the primitive streak. Some theorists suggested that conjoined twins develop as a result of the failed fusion of a single fertilized ovum. However a new hypothesis suggests that cranial fusion occurs between two separate embryos before the end of the 4th week of gestation. This can happen because the cranial neuropore is still open, which is responsible for the ultimate fusion and formation of
The D'Ambrosio Twins The D'Ambrosio Twins Bianca D'Ambrosio and Chiara D'Ambrosio (born April 28, 2005), also known collectively as the D'Ambrosio Twins, are American child actresses and musicians. The twins made their acting debut playing Summer Newman on the soap opera "The Young and the Restless". At the age of 6, Bianca and Chiara began starring together and separately in TV, films, print, music, and video projects. The twins were born in Los Angeles, California. In 2008 at the age of 3, the twins were cast in the role of Summer Newman on the soap opera, "The Young and the Restless" on CBS.