From the mists of early electron microscopy (EM) images there gradually emerged, during the 1950s and 1960s, long, rod-shaped structures. Various investigators missed them, dismissed them, or called them canaliculi, endoplasmic reticulum, or filamentous elements. Finally Slautterback (1963) and Ledbetter and Porter (1963) gave them a full description, recognized their ubiquity, and bestowed their final name, for now still in quotation marks, as “microtubules”.
“Fibrillae” had been noted in flagella and mitotic spindles as early as 1900, but their existence and relationship to one another were disputed. EM provided concrete evidence for their existence, although in one of the earliest EM images of dendritic microtubules the structures were described as “long tubular elements of the endoplasmic reticulum, about 180 Å wide and remarkably straight” (Palay, 1956). Better images of spindle microtubules came from many workers including Roth and Daniels (1962), and microtubules turned up more...
