Fig. 5. Fate of pharyngeal sensory neurons through metamorphosis. Persisting neurons are shown in color, neurons undergoing apoptosis in black, and newly born neurons with a dot. Individual sensilla are shown as arrowhead symbols. (A) Third larval instar: the dorsal pharyngeal sense organ (dps) consists of two groups of neurons, a and p1. Precise numbers of sensilla in the dps, dpo (dorsal pharyngeal organ) and vps (ventral pharyngeal sense organ) are unclear. lbn, labial nerve; lrn, labral nerve; pps, posterior pharyngeal sense organ. (B) Adult: the dorsal cibarial sense organ (dcso) corresponds to the conserved pps. The labral sense organ (lso) and the ventral cibarial sense organ (vcso) derive essentially from the dps. However, the vcso also includes two neurons of the dpo. Seven small sensilla of the lso as well as the fishtrap bristles (ftb; numbers in the diagram reduced) are born during metamorphosis. Remaining neurons of the dps and dpo are located along the accessory pharyngeal nerve (apn). pn, pharyngeal nerve.