A Reinvestigation of Cross-sections of Cilia

The cilium was one of the first cell organelles to be investigated with the electron microscope (see Manton and Clarke, 1952; Fawcett and Porter, 1954). Since then, this structure has been widely reinvestigated as improved techniques became available both to the electron microscopist and to the biochemist. In the study reported here, improvements in fixation and the use of the "Markham" rotation technique (Markham et al., 1963) have provided means for clearer observations on previously described appendages of the 9 + 2 complex of fibers and for a demonstration of additional structural details. Among the most complete morphological de-