adult antennal nerve [FBbt_00003980]

adult antennal nerve

ID: FBbt_00003980

Nerve that carries axons associated with the antenna and upper head capsule to the brain (It et al., 2014). It enters the brain at the level of the dorsal subesophageal zone (Eichler et al., 2024). Near the brain it consists of about 1700-1800 axons (Stocker, 1979; Stocker and Gendre, 1988). Approximately 1100-1200 of these are sensory fibers from the third antennal segment, mainly axons from olfactory receptor neurons that project to the antennal lobe ventrally, at its antero-ventral corner (Stocker, 1979; Stocker and Gendre, 1988; Kamikouchi et al., 2006). The remaining 500-600 fibers stem mainly from Johnston's organ neurons and mechanosensory sensilla of the anterior head capsule, which target neuropil domains outside of the antennal lobe, including the antennal mechanosensory and motor center (Stocker, 1979; Kamikouchi et al., 2006). A few fibers from this nerve project to the gnathal ganglion and the ventrolateral protocerebrum (Ito et al., 2014).

Stocker and Gendre provide the antennal nerve afferent counts based on TEM micrographs (Stocker and Gendre, 1988). Gross projection patterns within the brain were elucidated by Holmes-Blest reduced silver impregnation (Stocker et al., 1990). That the antennal nerve is composed of some 1200 third antennal segments and 500-600 fibers stemming from the JON and mechanosensory sensilla is based on two lines of evidence: 24hours after amputation of the funiculus, degeneration is seen in all but 500-600 fibers entering the antennal mechanosensory and motor center (Stocker et al., 1990); and Kamikouchi et al. (2006) used enhancer trap labelling and immunolabelling of JONs to trace their projections.