Reorganization of persistent motoneurons in a metamorphosing insect (Tenebrio molitor L., Coleoptera).
The present analysis outlines how the shape of motoneurons which persist through metamorphosis in the beetle Tenebrio molitor is regulated by cellular interactions. This study focused on the structural changes of prothoracic leg motoneurons. The fate of these neurons is described in normal metamorphic development, so as to provide a basis for experimental analysis. In a first experiment the prothoracic leg imaginal discs or part of these were extirpated in the prepupa or early pupa. In a second experiment the leg imaginal discs were rotated by 180 degrees in early larval instars of Tenebrio; the procedure caused a threefold leg anlage. Thereafter, the treated individuals continued to develop. In both experiments the effect of the operation on the structure of the dendritic trees of the persisting motoneurons was analyzed at the imaginal stage. In the first experiment the dendritic tree of the motoneurons is locally deleted. In the second experiment the branching index (quantitative description of dendritic arborization pattern) of the dendritic tree of the persisting motoneurons increased. Both experiments provided evidence that the shape of persistent leg motoneurons is stabilized and even regulated by cellular interactions during metamorphosis. Evidence is presented that sensory neurons are effective both in stabilization and regulation of the shape of persistent motoneurons.
Breidbach
O
O
Institut für Angewandte Zoologie, Rheinische Friedrich-Wilhelms-Universität, Bonn, Federal Republic of Germany.
D000671:Amputation, Surgical; D000818:Animals; D007866:Leg / Q000254:growth & development; D008675:Metamorphosis, Biological / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology; D013712:Tenebrio / Q000254:growth & development*