In The Tomb of the Cybermen (1967), veins and brains were visible through the domed head of the Cyberman Controller and similarly, in Attack of the Cybermen (1985) and "The Age of Steel" (2006), the Cyber-Controller's brain is visible through the dome.
In The Tomb of the Cybermen , from 1967, veins and brains were able to be seen through the domed head of the Cyberman Controller. Also, in Attack of the Cybermen, from 1985, and the Age of Steele, from 2006, the Cyber-Controller's brain is able to be seen through the dome.