Immunocytochemical localization of an insulin-like substance in the synganglion of the tick Ornithodoros parkeri (Acari: Argasidae).

Immunocytochemical staining based on the peroxidase-antiperoxidase method has shown that some neurosecretory cells (NSC) in the synganglion of the adult female tick Ornithodoros parkeri react with an antibody to bovine insulin. There are 18 regions of paraldehyde fuchsin-positive NSC of which three regions showed specific insulin-like immunoreactivity: anterolateral cheliceral, anteromedial stomodeal and posterior opisthosomal. Immunoreactivity can also be found in the extracellular surface of the neurilemma of the synganglion. This suggests a possible neurohemal site and release of neurohormone in a diffuse manner.