The afferent and efferent nerve endings of the outer hair cells of the rabbit were investigated electron-microscopically. The afferent nerve ending was 1.4 X 2.0 microns in size and contained small vesicles, spherical mitochondria, and occasionally multivesicular bodies. The partially thick and dense membranes on either side of the synaptic cleft were observed and this region of the synaptic cleft was high in electron density. This area was considered to be an active zone of the afferent nerve ending. The efferent nerve ending was 4.0 X 6.0 microns in size and contained many synaptic vesicles, many oblong mitochondria, and multivesicular bodies. Synaptic vesicles were concentrated at some sites opposite the synaptic cleft. This area was thought to be an active zone where vesicles discharge their contents into the synaptic cleft. Furthermore, in some places of the synaptic cleft there were gaps (0.16 X 0.68 microns) which contained small vesicles. The gaps in the synaptic cleft have been briefly discussed.

No abstract

Rabbits were exposed to 100 dB pure-tone sound at 2 kHz for 2 h. Electron microscopy was used to study the relationship between changes in the outer hair cells, afferent nerve endings and efferent nerve endings. There was no relationship found between the degree of changes produced in the afferent nerve endings and that the outer hair cells. However, there was a relationship demonstrable between the degree of changes seen in the efferent nerve endings and the infranuclear region of the outer hair cells. These findings show that acoustic trauma will damage most the infranuclear region of the outer hair cells, while efferent nerve endings are injured next and least affected are afferent nerve endings.

After contact with a dead rabbit in Baden-Wuerttemberg in southern Germany, three members of a family were infected with tularaemia in late summer 2007. The patients were a forest worker (Patient A) in his twenties, and his parents, both in their fifties. Tularaemia is very rare in Germany. From 2002 to 2006, between one and five cases were reported annually, with the exception of 2005 with 15 reported cases [1]. In 2007, 19 cases were reported, 11 of them in Baden-Wuerttemberg [2]. In the district in which the three cases occurred, no tularaemia cases had been reported in recent years.

The afferent and efferent nerve endings of the outer hair cells of the rabbit after acoustic exposure were investigated under the electron microscope. After acoustic stimulation, the afferent and efferent nerve endings of normal range were respectively 57 per cent and 64 per cent. This result suggests that half of the afferent and efferent nerve endings maintain their function under the conditions of this experiment. An abnormal inclusion body forming an oblong dense body and cistern in addition to the postsynaptic cisterna was observed. The active zone and the vesicular gap-structure of the synapse are discussed.