Dorsal longitudinal stretch receptor of Drosophila melanogaster larva - fine structure and maturation.

Insects possess two types of sensory neurons: ciliated type I sensory neurons that innervate external sensory organs and chordotonal organs, and type II sensory neurons that form a subepidermal plexus or innervate stretch receptors. Among stretch receptors, a dorsel longitudinal stretch receptor is highly conserved in insects, being found in all insect orders investigated. Here we describe the topology and anatomical structure of this receptor in the fruit fly embryo and larva using transmission electron microscopy and single cell staining for fluorescence microscopy. The receptor is composed of the dorsal bipolar dendrite neuron, which arises from an archetypal cell lineage, its sister glial cell and the peripheral glial cell accompanying the nerve. The neuron is situated among the muscles in the dorsal body wall on the intersegmental nerve. Its two dendrites stretch the length of the segment to the segmental folds. The neuron is wrapped by both glial cells and surrounded by a common basal lamina, which fans out at the dendritic tips to attach them to the epidermal cells at the segmental borders.

The function of the cercal sensory system in escape behavior of the cave cricket Troglophilus neglectus Krauss.

Long cerci of cave crickets Troglophilus neglectus Krauss (Rhaphidophoridae, Orthoptera) are, in contrast to other investigated species, oriented perpendicularly to the ground. Behavioural experiments indicated that cave crickets detect wind direction and respond to stimulation by jumping away from the stimulus. Directed wind puffs deflect filiform sensory hairs on the cerci, trigger physiological responses of their sensory neurons and change activity of interneurons that control the escape direction. Two local interneuron pairs, one non-spiking and one spiking, were identified using intracellular recording and subsequent dye injection techniques. The non-spiking interneuron responds to the puffs from sides with a large depolarization and to the puffs from the front and back of the animal with a small depolarization. After stimulation from the ipsilateral side the spiking interneuron responds with a burst of spikes at the onset of stimulation and, after stimulation from the contralateral side, it responds with a burst of spikes at the onset and at the end of the stimulation.