In this diagram of an hemisegment A1-A7, anterior is left and dorsal is up. Each sensory cell is represented by a closed shape. Note however that hemisegment A1 may be slightly different (for example, the es organ vp4a is sometimes missing, V. Orgogozo, personal observations).
multidendritic neuron (red)
is an external sensory organ composed of four cells (from top to bottom: socket cell, shaft cell, sheath cell and neuron (big yellow circle)). The dendrites of sensory neurons are indicated as a line.
is a mono-scolopidium chordotonal organ composed of three cells (two accessory cells and a neuron (blue triangle)).
Sensory organs are arranged in three clusters: the dorsal cluster (sensory organs whose names start with d), the lateral cluster (sensory organs whose names start with l), and the ventral cluster (sensory organs whose names start with v). The ventral cluster has been further refined into the v' and v regions.