Mechanism for sensillum fluid flow in trichogen and tormogen cells of Phormia regina (Meigen) (Diptera: Calliphoridae)

Abstract

Electron microscope observations of the tormogen and trichogen cells of the black blow fly ( Phormia regina) chemoreceptor sensillum indicate that an osmium zinc iodide positive (ZIO) substance(s) is conveyed by transport vesicles into the sensillum fluid cavity. Large concentrations of this material(s) were noted between adjacent microvilli which project into the fluid cavity. This particular localization of ZIO-positive substances suggests that they may form part of a fixed hyperosomotic environment which subsequently assists in the flow of the sensillum fluid into the fluid cavity. The formation of ZIO positive material(s) and chemosensory nerve firing are both inhibited by p-chloromercuri benzoate (PCMB, 5 x 10 −4M). Based on the binding affinity of PCMB to sulfhydryl groups, the ZIO-stained substance which is transported to the sensillum fluid cavity may be lipoprotein.