Trichites of "fossette" and dorsal brush cilia

Description:

Infraciliature (right lateral view) of the prorodontid ciliate, Placus luciae (Kahl,1926) Kahl,1930. The cell is ovoid and slightly laterally compressed. The pellicle has broad slightly spiral ridges separated by narrow furrows. The small oval oral aperture is apical anterior, surrounded by a ring of unciliated kinetosomes. The cytopharynx is supported by fine trichites. The somatic ciliature uniform, with cilia. There is a "dorsal brush" (blue arrow), about 1/4 to 1/3 cell length, composed of a double parallel row of kinetosomes bearing longer cilia. It arises adjacent to the oral aperture and terminates at a ventral circular "pit" or "fossette" which has a supporting ring of transversely oriented trichites (yellow arrow). The function of this structure is unknown. The ovoid macronucleus is centrally located. The contractile vacuole is posterolateral. Collected from a slow-flowing freshwater stream near Boise, Idaho.Stained by the silver carbonate technic (see Foissner, W.Europ. J. Protistol.27,313-330;1991). Brightfield.