Glossary
Like the rest of this website, the glossary is a work in progress. If we’ve missed a term, please contact us to let us know the term and references.
Central nodule
A central nodule is the thickly silicified area located between the proximal raphe ends in raphid diatoms. It is often thickened in both valve and girdle views. It is the site where the silica deposition vesicle deposits the first silica during valve formation.
Image Credit: Sarah Spaulding
Image Credit: Marina Potapova
Image Credit: Gene Stoermer
Image Credit: Sarah Spaulding
Scanning electron micrograph of the central nodule in Diploneis. It is unornamented (lacks areolae) and often has thicker silica than other parts of the valve.
Image Credit: Marina Potapova
Scanning electron micrograph of the internal view of a valve of Hippodonta. The central nodule lies between the proximal raphe ends.
Image Credit: Gene Stoermer
Light micrograph of the central nodule in Caloneis amphisbaena. The thicker silica of the central nodule is distinct between the proximal raphe ends.