01940nas a2200229   4500008004600000245011700046210006900163300001400232490000700246520120500253653001201458653002601470653001101496653002501507653002801532653000901560653003501569100001801604700001701622700002101639856005001660       Submitted                   eng d     00aMorphology and physiology of the prosternal chordotonal organ of the sarcophagid fly Sarcophaga bullata (Parker)0 aMorphology and physiology of the prosternal chordotonal organ of  a444 - 4540 v533 aThe anatomy and the physiology of the prosternal chordotonal organ (pCO) within the prothorax of Sarcophaga bullata is analysed. Neuroanatomical studies illustrate that the approximately 35 sensory axons terminate within the median ventral association centre of the different neuromeres of the thoracico-abdominal ganglion. At the single-cell level two classes of receptor cells can be discriminated physiologically and morphologically: receptor cells with dorso-lateral branches in the mesothoracic neuromere are insensitive to frequencies below approximately 1 kHz. Receptor cells without such branches respond most sensitive at lower frequencies. Absolute thresholds vary between 0.2 and 8m/s(2) for different frequencies. The sensory information is transmitted to the brain via ascending interneurons. Functional analyses reveal a mechanical transmission of forced head rotations and of foreleg vibrations to the attachment site of the pCO. In summed action potential recordings a physiological correlate was found to stimuli with parameters of leg vibrations, rather than to those of head rotation. The data represent a first physiological study of a putative predecessor organ of an insect ear.10aAnimals10aDiptera/*anatomy &amp10aFemale10ahistology/physiology10aInterneurons/physiology10aMale10aMechanoreceptors/*anatomy &amp1 aStölting, H.1 aStumpner, A.1 aLakes-Harlan, R.  uhttps://sarcophagidae.myspecies.info/node/463