Meeting Abstract
Larval Manduca sexta have become an important model system for understanding the neuromechanics of soft body locomotion. In addition to Manduca’s readily accessible nervous system, its tissues and body structures have been described in increasing detail throughout the 20th century. While dissection techniques and talent have captured most of the musculature and body wall, they all rely on flattening the three-dimensional structure which causes considerable distortion and tissue damage. To gain better insights into the control and mechanical properties of the abdominal prolegs we have used X-ray microtomography of intact animals to capture structures at tens of micron of resolution. Here we describe intact proleg muscle morphology, highlighting previously undiscovered fiber bundles and attachments, as well as differences in fiber quantity and attachment area between anterior and posterior segments. Larvae were fixed, stained and scanned to distinguish the primary tissues types with minimal distortion. Structures were labelled and morphological statistics were calculated from these three-dimensional models. In addition to muscles described in the literature attached to the proleg planta (PPRM), we found three previously undescribed groups of fibers that attach to the body wall in a highly stereotyped manner. Data from several animals revealed an increased number of fibers in specific muscle groups in posterior segments. Additionally, there is a reduction in the cross-sectional area of individual fibers and a greater total muscle volume. Total fiber volume for all muscles inserting in the planta show an approximately two-fold increase from segments A3 to A6.
