Reconstruction of oral cavity of Tetrahymena pyriformis utilizing high voltage electron microscopy.

Reconstruction of the oral cavity from 17 0.5 mum thick serial sections observed with a high voltage electron microscope (JEM-1000, operated at 1000 kV) has enabled us to describe the in situ shape of the cavity, the orientation of the membranelles, oral ribs, cytostomal lip and forming food vacuole of Tetrahymena pyriformis. The study also showed that many different sets of microtubules encircle the oral cavity forming an interwoven, basket-like structure around the cavity thus providing it with considerable structural rigidity. By correlating results obtained from the reconstruction with results obtained from scanning electron microscopy and freeze-fracturing we have been able to elucidate the probable mechanism of how food particles are propelled into and through the oral cavity.