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UBC Theses and Dissertations

Ultrastructure of the rostral sensory organs of the water bug, Cenocorixa bifida (Hungerford), (Hemiptera) Lo, S. Esther


The sensory organs in the transverse grooves of the dorsal labium of the water bug, Cenocorixa bifida, (Hungerford) (Hemiptera) were studied with the electron microscope. It was found that each sense organ is supplied by a single, bipolar neuron, which, together with its sheath cell, forms a sensory unit. The dendrite of the neuron is modified into various structures along its length; it has a root system, two basal bodies, and an axial filament complex. These structures are characteristic of many mechanoreceptors and chemoreceptors in insects. The sheath cell surrounding the dendrite possesses many characteristic fine structures, such as the desmosomes and the microtubules. According to their ultrastructure and their location near the mouth opening, it is most likely that these sensory organs are chemoreceptors. The significance of the presence of the ciliary regions in the dendrites of these organs is suggested to be related to the regeneration of the distal portion of the dendrite which may be torn off during the process of moulting. The axial filament complex may also serve as an internal support in the dendrite.

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