Tetrahymena is an oligohymenophoran ciliate and a very common freshwater ciliate. It is usually used to demonstrate the levels of organization and cortical features that are characteristic of the ciliate taxa.

The pictures below are of a silver nitrate-stained specimen of Tetrahymena.

The cilia themselves do not stain, but their location can be identified because the region between the cilium and the kinetosome takes up silver ions. Collectively, all the stained kinetosomes in a row represent a kinety although the other structures in a kinety have not stained. The kineties of the somatic region of the cell constitute the kinetome and the polykineties of the oral area constitute the oral apparatus.

After the first ciliate lab, you may already have an understanding of the following structures below that you need to identify and label clearly in your drawings. Make sure you have a ventral view and a lateral view of Tetrahymena.

Include the following structures and morphology:

(Insert slides with labels of each structure)
General Morphology
Basal Bodies

These will be stained by the silver nitrate and will appear as little brown dots on the surface of Tetrahymena.

These will appear as parallel lines of dots (basal bodies) running down the length of the cell surface.

Primary and Secondary Meridians (alveolar boundaries)
The primary meridian is a line of kineties with basal bodies while the secondary meridian is the next meridian over with no kineties.
Oral Apparatus
The oral apparatus is located on the anterior end of the cell and can be easily seen as a small cavity in the ventral view of the cell.
Buccal Cavity
Nothing unusual. You have seen other buccal cavities by now and can easily identify this structure in Tetrahymena.
Buccal Overture

Again nothing is surprising about this opening in Tetrahymena.


Located on the right hand side of the buccal overture. There are three regions of polykineties: P1, P2, and P3 and these can be found in the buccal cavity and are quite distinct. You may have to focus up and down to see all three regions of polykineties.
Located on the left hand side of the buccal overture. There is only one region of haplokinety and appears as a curved line in the ventral view of Tetrahymena.

Contractile Pore
This structure can be seen at the posterior end of the organism in the dorsal view. It appears as a small darkly stained hole on the right side of the organism.

These are a drawings demonstrating ventral and dorsal view of Tetrahymena vorax and Tetrahymena pyriformis under the light microscope with the 100x lens. Try to focus in at the buccal cavity and find all three regions of polykineties. As well, focus on the alveolar boundaries and label primary and secondary meridians clearly, noting their patterns and presence or absence of basal bodies.