The cells of Boettcher in the bat, Pteronotus p. parnellii.

The structural characteristics, distribution and intercellular relationships of the cells of Boettcher were studied in the mustache bat, Pteronotus P. parnellii. The cells of Boettcher have many structural features similar to those described in other mammals, but in Pteronotus they are distributed throughout the cochlea and are associated with relatively large amounts of secretory and/or absorptive material. Much of this material seems to be derived from or contribute to, a darkly staining upper layer of the basilar membrane. This material accumulates in elaborate microvillus-filled intercellular channels which are restricted to an area near the basilar membrane. The channels communicate with the basilar membrane surface through wide intercellular spaces and through small canals. The microvillus-filled channels are confluent with large extracellular spaces between Boettcher's cells and a single row of cells which form the floor of the outer tunnel. The latter have irregular shaped nuclei, contain many vacuoles and like Boettcher's cells, are associated with large amounts of basilar membrane-like material. Observations on Pteronotus, as well as other species of bats, do not support concepts relating Boettcher's cells to hair cell innervation patterns or to high frequency hearing.