Milestones of research towards understanding of laterality disorders. Since the first description of laterality defects around 1600 by Fabrizio several milestones can be identified (marked with red arrows on the time scale) which led to a sharp increase in knowledge with regard to the origin of laterality defects. This included the first description of bronchiectasis in combination with situs inversus totalis by Siewert in 1904  and Kartagener in 1933  followed by the demonstration that ciliary defects are the underlying cause of Kartagener’s syndrome in 1976 [17,18]. The demonstration of motile monocilia at the mouse node in 1994  followed by the identification of the first asymmetrically expressed genes in 1996 [37,38], later known as members of the Nodal signaling cascade, opened the wide field of research on the genetic and molecular levels which led to our current knowledge about the connection of situs inversus and ciliary abnormalities. It is worth mentioning here that around the same periods, Antony van Leeuwenhoek already in 1675 described a living protozoan ‘provided with diverse incredibly thin feet, or little legs, which were moved very nimbly’ and that the term ‘cilia’ was probably first used by OF Muller in 1786 (reviewed in [143,144]).