Simona Padurariu1, Christof Röösli2, Rasmus Røge3, Allan Stensballe4, Mogens Vyberg5, Alex Huber2, Michael Gaihede6. 1. Department of Otorhinolaryngology, Head and Neck Surgery and Audiology, Aalborg University Hospital, Aalborg, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark. Electronic address: s.padurariu@rn.dk. 2. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zürich, University of Zurich, Zurich, Switzerland. 3. Institute of Pathology, Aalborg University Hospital, Aalborg, Denmark. 4. Department of Health Science and Technology, Aalborg University, Aalborg, Denmark. 5. Department of Clinical Medicine, Aalborg University, Aalborg, Denmark; Institute of Pathology, Aalborg University Hospital, Aalborg, Denmark. 6. Department of Otorhinolaryngology, Head and Neck Surgery and Audiology, Aalborg University Hospital, Aalborg, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
Abstract
BACKGROUND: Middle ear physiology includes both sound pressure transmission and homeostasis of its static air pressure. Pressure gradients are continuously created by gas exchange over the middle ear mucosa as well as by ambient pressure variations. Gas exchange models require actual values for regional mucosa thickness, blood vessel density, and diffusion distance. Such quantitative data have been scarce and limited to few histological samples from the tympanic cavity (TC) and the antrum. However, a detailed regional description of the morphological differences of the TC and mastoid air cell system (MACS) mucosa has not been available. The aim of the present study was to provide such parameters. METHODS: The study included sets of three histological H&E-slides from 15 archived healthy temporal bones. We performed a comparison of the mucosa morphology among the following regions: (1) anterior TC; (2) inferior TC; (3) posterior TC; (4) superior TC; (5) MACS antrum; (6) superior MACS; (7) central MACS; (8) inferior MACS. RESULTS: Regions (1)-(3), situated below the inter-attico-tympanic diaphragm, had the largest proportion of high respiratory epithelium, cilia and loose lamina propria within the mucosa, as well as the thickest mucosa and the largest diffusion distance. Regions (6)-(8), situated above the diaphragm, had the thinnest mucosa, the shortest distance to the blood vessels, together with the largest proportion of flat epithelium and very few cilia. Regions (4)-(5), still supradiaphragmatic, had intermediary values for these parameters, but generally closer to regions (6)-(8). The blood vessel density and the proportion of active mucosa were not significantly different among the regions. CONCLUSION: Mucosa of regions (1), (2) and (3) represented a predominantly clearance-specific morphology, whereas in regions (4)-(8) it seemed adapted to gas exchange. However, the lack of statistically significant differences in blood vessel density and proportion of active mucosa indicated that all regions could be involved in gas exchange with the highest adaptation in the superior MACS. This pattern divides the middle ear functionally along the inter-attico-tympanic diaphragm rather than the anatomical division into TC and MACS.
BACKGROUND: Middle ear physiology includes both sound pressure transmission and homeostasis of its static air pressure. Pressure gradients are continuously created by gas exchange over the middle ear mucosa as well as by ambient pressure variations. Gas exchange models require actual values for regional mucosa thickness, blood vessel density, and diffusion distance. Such quantitative data have been scarce and limited to few histological samples from the tympanic cavity (TC) and the antrum. However, a detailed regional description of the morphological differences of the TC and mastoid air cell system (MACS) mucosa has not been available. The aim of the present study was to provide such parameters. METHODS: The study included sets of three histological H&E-slides from 15 archived healthy temporal bones. We performed a comparison of the mucosa morphology among the following regions: (1) anterior TC; (2) inferior TC; (3) posterior TC; (4) superior TC; (5) MACS antrum; (6) superior MACS; (7) central MACS; (8) inferior MACS. RESULTS: Regions (1)-(3), situated below the inter-attico-tympanic diaphragm, had the largest proportion of high respiratory epithelium, cilia and loose lamina propria within the mucosa, as well as the thickest mucosa and the largest diffusion distance. Regions (6)-(8), situated above the diaphragm, had the thinnest mucosa, the shortest distance to the blood vessels, together with the largest proportion of flat epithelium and very few cilia. Regions (4)-(5), still supradiaphragmatic, had intermediary values for these parameters, but generally closer to regions (6)-(8). The blood vessel density and the proportion of active mucosa were not significantly different among the regions. CONCLUSION: Mucosa of regions (1), (2) and (3) represented a predominantly clearance-specific morphology, whereas in regions (4)-(8) it seemed adapted to gas exchange. However, the lack of statistically significant differences in blood vessel density and proportion of active mucosa indicated that all regions could be involved in gas exchange with the highest adaptation in the superior MACS. This pattern divides the middle ear functionally along the inter-attico-tympanic diaphragm rather than the anatomical division into TC and MACS.
Authors: Michael W Mather; Steven Powell; Benjamin Talks; Chris Ward; Colin D Bingle; Muzlifah Haniffa; Jason Powell Journal: Expert Rev Mol Med Date: 2021-08-18 Impact factor: 7.615