THE FLAGELLAR APPARATUS AND CANAL STRUCTURE IN PROROCENTRUM MICANS (DINOPHYCEAE)

We have determined the three-dimensional structure of the flagellar ap paratus in Prorocentrum micans Ehrenberg (Dinophyceae). The flagellar apparatus consists of two basal bodies that lie at approximately a 35 degrees angle to one another. Each basal body bears a typical dinophyc ean complement of microtubular and fibrous components. Unlike the majo rity of Dinophyceae, the longitudinal microtubular root lies adjacent to the longitudinal basal body and abuts the transverse basal body. Th e transverse microtubular root is associated with an extension of micr otubules that is directed posteriorly (dorsal, using proposed terminol ogy) into the cell to a region adjacent to the nucleus. On the opposit e side of the flagellar apparatus, the microtubules of the peduncle ex tend posteriorly (dorsal, using proposed terminology) from the flagell ar canal region. The microtubules extend for several micrometers and t he peduncle is closely associated with a complex striated collar that circumscribes the flagellar canal and its components. We report on the three-dimensional nature of the flagellar canal and accessory pore ca nal region. We conclude that the flagellar canal and accessory pore ca nal are not attached to each other and that the 'Prorocentrum' type of flagellar apparatus and cell architecture is most likely the result o f episome/hyposome compression.