Morphometric analysis of the tracheal walls of the harvestmen Nemastoma lugubre (Arachnida, Opiliones, Nemastomatidae) |
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| Authors: | Schmitz Anke Perry Steven F |
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| Affiliation: | 1. Buffalo Neuroimaging Analysis Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA;2. IRCCS, Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy;3. Center for Biomedical Imaging at Clinical Translational Science Institute, University at Buffalo, State University of New York, Buffalo, NY, USA;4. Jacobs Comprehensive MS Treatment and Research Center, Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA;1. Riphah Institute of Pharmaceutical Sciences, Riphah International University, Islamabad, Pakistan;2. Health management center, Shenzhen University general hospital, Shenzhen University clinical medical academy, Shenzhen University Shenzhen, 518060, China;3. National Center for Bioinformatics, Quaid-i-Azam University, Islamabad, Pakistan;4. Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada;5. State Key Laboratory of Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen, China |
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| Abstract: | The tracheal system of harvestmen consists of two stem tracheae, which give rise to higher order tracheae that supply the extremities and internal organs. In this study, we used stereological morphometric methods to investigate diffusing capacities of the walls ('lateral diffusing capacity') of the tracheae of adult males and females of Nemastoma lugubre. Diffusing barriers of the tracheal walls tend to be thinnest (0.17-0.19 microm) for the smallest tracheae (inner diameter 0.5-2 microm). In other tracheal classes the diffusing barriers increase with increasing diameters. Calculation of the mass-specific diffusing capacity for oxygen (D(O2)) of the walls of all higher order tracheae revealed 10.57 microl min(-1)g(-1)kPa(-1) for the females (mean body mass 3.8 mg) and 25.23 microl min(-1)g(-1)kPa(-1) for the males (mean body mass 1.4 mg). In both animal groups, the main D(O2) (58-67%) lies in the tracheae with an inner diameter of 0.5-2 microm, but also tracheae up to an inner diameter of 20 microm allow gas exchange via the tracheal walls. Stem tracheae are of no importance for lateral diffusion. Our results are consistent with the hypothesis that the functional morphology of the tracheal system of harvestmen represents an 'intermediate state' between the tracheal system of insects in which gas exchange is focused on the distal portions and that of spiders, in which the walls of all tracheae serve in gas exchange. |
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