Transmission electron micrographs (TEM) of Calkinsia aureus showing the feeding apparatus. The ventral flagellum was disorganized in all sections (A-D at same scale, bar = 1 μm; E-G at same scale, bar = 1 μm). A. Section showing the oblique striated fibrous structure (OSF) and the VR along the wall of the flagellar pocket (FLP). Arrow points out the LMt and the DL. B. Section through the congregated globular structure (CGS), the OSF and the feeding pocket (FdP). The VR extends to the right. The arrow points out the LMt and the DL, which extend from the VR to the IR and support the dorsal half of the FLP. C. Section showing the VR over the CGS. Arrows show the LMt and DL. D. The VR crosses over the CGS and extends to right side of the FdP. Most of the wall of the FLP is supported by the LMt and DL (arrows). E. A striated fiber (double arrowhead) supports the left side of the FdP and extends from the left side of the CGS. Arrows indicate the extension of the LMt and DL. F. Section through the beginning of the vestibulum (V) and the striated fiber (double arrowhead). G. The V is enlarged and the CGS remains at both sides of the FdP. H. High magnification of FdP. I. Tangential TEM section showing the VR with an electron dense fiber along the feeding pocket and a tomentum (T) of fine hairs. J. Longitudinal section through the CGS and the OSF. Six ventral root microtubules embedded within the electron dense fibers (arrowheads). K. High magnification view of the VR supporting the FdP shown in F. Double arrowhead indicates the striated fiber and the six arrowheads indicate the electron dense fibers of the VR. (H-K, bars = 500 nm).