Ultrastructure of a Sensory Receptor in the Abdominal Body Wall of Rhodnius Prolixus
The abdominal body wall of the blood-feeding insect, Rhodnius prolixus, contains symmetrically arranged sense organs which respond to pressure applied from the haemocoelic side. The organs, which occur on either side of the midline in abdominal segments III to VI, discharge with increasing frequency in response to increasing pressure, and do not accomodate (Chiang and Davey, 1988). Under the light microscope, the receptor appears as a plaque embedded in the body wall. The anterior end of the plaque is joined by a small process to a branch of the segmental nerve in which is located the cell body of the receptor. Extending along the midline of the plaque is a heavily stained filamentous strand which, at its distal end, enlarges into a rod-like structure. The following results describe the appearance of this rod-like structure as revealed by serial thin-section electron microscopy.