Morphological characterization of antennal-lobe projection neurons in the olfactory pathway of heliothine moths

Abstract

The olfactory sensory system is a phylogenetically old system highly important for both the survival and reproduction in most animals. Its organization and function shows striking similarities across phyla, making it possible to study its general underlying properties through the use of different species. The moth has proven to be a particularly suitable model organism for studying this system, as it has an exceptionally well-developed sense of smell, and a relatively moderate brain complexity. In this thesis, the part of the central olfactory pathway forming connections between the primary brain center and higher processing centers has been studied through the use of the heliothine moths Heliothis virescens and Helicoverpa armigera. Second-order olfactory projection neurons have been labeled through a dual electrophoretic staining technique, where one approach targeted the dendrites of projection neurons in the antennal-lobe, and one targeted the projection neuron somata confined within the lateral cell cluster of the antennal-lobe. In addition to complementing previous reports on morphological characteristics typifying antennal-lobe projection neurons confined within three primary antennal-lobe tracts, the present study contributes new findings previously not described in heliothine moths.