When the famous Spanish physician Santiago Ramón y Cajal looked through his microscope in 1910, he discovered irregular and "transparent lumps" that appeared throughout the nucleus of a neuron. What these nuclear speckles are all about is still largely unclear, even though the biological and medical sciences have experienced several revolutions since then. "Even though we know quite a bit about their function, we didn't know how nuclear speckles originate, i.e. what their core consists of," says Tuçe Akta from the Max Planck Institute for Molecular Genetics.