Because information regarding neural and sensory functions of ticks is scarce, the aim of the present study was to ascertain the neuronal projection patterns of olfactory sensilla from Haller's organ to the olfactory lobes of the synganglion in Amblyomma sculptum adults. Additionally, the aim was to perform three-dimensional (3D) reconstruction of the glomeruli in the olfactory lobes. Unfed female and male adults of this tick species were immobilized, Haller's organ was sectioned, and the olfactory nerves were labelled with a neuronal tracer (1% dextran tetramethylrhodamine). The labelled olfactory lobes were observed under a confocal laser scanning microscope and the images were analyzed using the Reconstruct software. The neuronal projection originating from the olfactory sensilla of Haller's organ was found to be strictly confined to the olfactory lobes of the synganglion, which were organized into glomeruli. Males and females presented corresponding round-shaped glomeruli in the olfactory lobes. The number of glomeruli ranged from 26 to 30 in the males and 24-29 in the females. Positive correlations regarding the glomeruli volumes (μm3) intrasexually (females: r = 0.85, P < 0.05) and intersexually (r = 0.81, P < 0.05) were observed. This is the first report on 3D reconstruction of the olfactory lobes of a tick species.
Keywords: Amblyomma cajennense complex; Glomeruli; Neuronal projection; Synganglion; Tick olfaction.
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