Cirri are compond ciliary structures found in stichotrich ciliate species. This is an image of a midventral cirrus from Tetmemena pustulata. These structures serve not only for cell locomotion but likely provide sensory input to the cell. The number of basal bodies in these structures vary depending on the cirrus type and the species, from as few as a couple dozen to several hundred. As seen in this longitudinal section through a cirrus, not all basal bodies are necessarily ciliated. These structures also have extensive microtubule networks associated with them that extend in several different directions throughout the cells protoplasm. A single mitochondria is present in the micrograph, which exhibits tubular cristae that are typical of protist mitochondria. Magnification 37500X.