Structure of tracheae and the functional implications for collapse in the American cockroach

Abstract

The tracheal tubes of insects are complex and heterogeneous composites with a microstructural organization that affects their function as pumps, valves, or static conduits within the respiratory system. In this study, we examined the microstructure of the primary thoracic tracheae of the American cockroach (Periplaneta americana) using a combination of scanning electron microscopy and light microscopy. The organization of the taenidia, which represents the primary source of structural reinforcement of the tracheae, was analyzed. We found that the taenidia were more disorganized in the regions of highest curvature of the tracheal tube. We also used a simple finite element model to explore the effect of cross-sectional shape and distribution of taenidia on the collapsibility of the tracheae. The eccentricity of the tracheal cross-section had a stronger effect on the collapse properties than did the distribution of taenidia. The combination of the macro-scale geometry, meso-scale heterogeneity, and microscale organization likely enables rhythmic tracheal compression during respiration, ultimately driving oxygen-rich air to cells and tissues throughout the insect body. The material design principles of these natural composites could potentially aid in the development of new bio-inspired microfluidic systems based on the differential collapse of tracheae-like networks.

Fluorescent dyes and probes for super-resolution microscopy of microtubules and tracheoles in living cells and tissues

“…The observed direct correlation is not surprising since the main function of taenidia is to keep the tracheole open for air flow and bigger diameter tracheoles require thicker taenidia with larger spacing. 30 For the first time, it allowed us to identify 6-carboxy isomers of 580CP and SiR dyes as chitin-specific stains compatible with STED nanoscopy. We took advantage of this knowledge and recorded two-colour STED images of tracheole taenidia surrounded by the tubulin network of tracheole cells stained with 580CP–LTX and SiR–COOH ( Fig.…”

Comparison of the tracheal systems ofAnopheles sinensisandAedes togoilarvae using synchrotron X-ray microscopic computed tomography (respiratory system of mosquito larvae using SR-μCT)

“…The frequency can be measured from consecutive dynamic movements of tracheal system such as peristaltic waves. The rhythmic tracheal movement during respiration might be induced by combined effects of the macroscale geometry, microscale organization, and mesoscale heterogeneity (Webster, Socha, Teresi, Nardinocchi, & De Vita, ). The emission rate of CO 2 is affected by the intratracheal CO 2 level and the opening area of spiracles (Pendar et al, ).…”

The Auditory Mechanics of the Outer Ear of the Bush Cricket: A Numerical Approach

“…For instance, it is known that the elastic properties of the AT wall are not isotropic. However this is not reflected in the input values used in the simulation due to lack of experimental data, and the values used are based on the results of the tests on the AT of the American cockroach Periplaneta americana given in (26).…”

“…In our model, we make the simplifying assumption that the elastic properties of the wall are isotropic. The values we adopted in Table 1 are based on the experimental results given in (26) for an American , where it has been demonstrated that the AT of this species has a mean value of 1.7 GPa and 0.3 for E and ν, respectively. We test the impact of the material properties of the AT wall on pressure gain in the ranges 1-20 GPa, 0-0.5, 1000-1300 kg/m 3 , for E, ν and ρ s respectively, which are the values provided for insect cuticle in (27).…”