| Abstract: | The present study reveals a deficiency in the number of ciliated basal bodies along 180° rotated ciliary rows (IRs) in Tetrahymena. This feature is common to IRs recently generated in young clones with stable corticotypes (total number of ciliary rows per cell), irrespective of the number of IRs present per cell or their cellular location, and is found before the cell loses any of the IRs. In cells bearing three IRs, the IRs on the two sides of the inversion immediately next to normal ciliary rows (junctures) exhibit an even greater deficiency in ciliated basal bodies, compared to the IR located internally between two other IRs; the normal ciliary rows flanking the inversion are also somewhat deficient. These observations show that the IRs of Tetrahymena are structurally deficient, hence developmentally defective, and suggest that they are intrinsically unstable. We propose that basal body development along IRs tends to be truncated before the stage of ciliation; such basal bodies would fail to acquire the potential to serve as nucleating centers for new basal body development in the next round of basal body proliferation, leading to the eventual loss of the IRs. © 1992 Wiley-Liss, Inc. |
