The case of the “S-shaped tubule”: how over-user-friendly nomenclature can lead to a century of embryological errors

StandardizeWd nomenclature is important to biology. Anatomical naming usually uses standard Greek- or Latin-derived terms to describe shape, but sometimes draws comparisons with everyday objects, aiming to reduce ambiguity and increase clarity. In the case of developing kidney, it did the opposite. In 1883 and 1889, two stages of nephron development were named after typographical characters, comma and ‘S’. This caused confusion in 3 ways; (i) an ‘S’ shape can be seen in different ways at different phases of nephron development, encouraging stage misidentification; (ii) ‘S’ has a completely different shape in Roman and Fraktur (‘Germanic’) fonts, used in a still-cited paper; (iii) a printed, rather than cursive, ‘S’ implied a stand-alone object, causing authors wrongly to represent S-shaped nephrons as unconnected. This story acts as a warning against making names so easy that they give an illusion of understanding without the need to check the original source.