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
Toxic Twins one of the duo's main influences, the "Glimmer Twins", the nickname for Mick Jagger and Keith Richards of the Rolling Stones. Additionally, it may have inspired other musical nicknames, like the "Terror Twins" - Def Leppard's Phil Collen and Steve Clark; and "The Muddy Twins" - Hanoi Rocks' Michael Monroe and Andy McCoy as well as the "Liverpool Twins" John Lennon and Paul McCartney, and the "Jersey Twins" Jon Bon Jovi and Richie Sambora. Mötley Crüe's Nikki Sixx and Tommy Lee were also known as the Terror Twins. Toxic Twins The Toxic Twins is a nickname given to lead singer