Fig. 2.

Morphology of and physiological recordings from olfactory sensilla. (A) Arrow indicates a single-walled trichoid sensillum from A. gambiae. (B) A double-walled grooved peg sensillum from A. gambiae. A and B are reprinted from ref. 179. (C) Single-sensillum recording method. An electrode is inserted in the lymph (L) of a sensillum, an odor stimulus is delivered, and action potentials are recorded from the ORNs. AC, accessory cells; EC, epidermal cells. Reprinted with permission from ref. 180. (D) Physiological recording. The bar above the trace indicates the 0.5-s odor stimulus. Action potentials of large amplitude derive from one ORN in the sensillum, and action potentials of smaller amplitude derive from the other ORN. In this trace, the ORN that produces large action potentials is excited by the odor.