title: Implicit mechanistic role of the collagen, smooth muscle, and elastic tissue components in strengthening the air and blood capillaries of the avian lung.
abstract: To identify the forces that may exist in the parabronchus of the avian lung and that which may explain the reported strengths of the terminal respiratory units, the air capillaries and the blood capillaries, the arrangement of the parabronchial collagen fibers (CF) of the lung of the domestic fowl, Gallus gallus variant domesticus was investigated by discriminatory staining, selective alkali digestion, and vascular casting followed by alkali digestion. On the luminal circumference, the atrial and the infundibular CF are directly connected to the smooth muscle fibers and the elastic tissue fibers. The CF in this part of the parabronchus form the internal column (the axial scaffold), whereas the CF in the interparabronchial septa and those associated with the walls of the interparabronchial blood vessels form the external, i.e. the peripheral, parabronchial CF scaffold. Thin CF penetrate the exchange tissue directly from the interparabronchial septa and indirectly by accompanying the intraparabronchial blood vessels. Forming a dense network that supports the air and blood capillaries, the CF weave through the exchange tissue. The exchange tissue, specifically the air and blood capillaries, is effectively suspended between CF pillars by an intricate system of thin CF, elastic and smooth muscle fibers. The CF course through the basement membranes of the walls of the blood and air capillaries. Based on the architecture of the smooth muscle fibers, the CF, the elastic muscle fibers, and structures like the interparabronchial septa and their associated blood vessels, it is envisaged that dynamic tensional, resistive, and compressive forces exist in the parabronchus, forming a tensegrity (tension integrity) system that gives the lung rigidity while strengthening the air and blood capillaries.
authors.affiliation: Department of Zoology, University of Johannesburg, South Africa. jmaina@uj.ac.za
authors.forename: John N
authors.initials: JN
authors.lastname: Maina
authors.forename: Sikiru A
authors.initials: SA
authors.lastname: Jimoh
authors.forename: Margo
authors.initials: M
authors.lastname: Hosie
mesh_terms: D000818:Animals; D001980:Bronchi / Q000033:anatomy & histology / Q000502:physiology; D002196:Capillaries / Q000033:anatomy & histology*; D002645:Chickens / Q000033:anatomy & histology*; D003094:Collagen / Q000032:analysis*; D004547:Elastic Tissue / Q000033:anatomy & histology*; D008168:Lung / Q000098:blood supply / Q000648:ultrastructure*; D008854:Microscopy, Electron; D009130:Muscle, Smooth / Q000033:anatomy & histology*
chemical_list: D003094:Collagen
references.citation: Respir Physiol. 1973 Jul;18(2):188-93
references.pmid: 4730750
references.citation: Proc Natl Acad Sci U S A. 2001 Jul 3;98(14):7765-70
references.pmid: 11438729
references.citation: J Appl Physiol. 1964 Mar;19:236-42
references.pmid: 14155287
references.citation: J Cell Sci. 2003 Apr 1;116(Pt 7):1157-73
references.pmid: 12615960
references.citation: Am Rev Respir Dis. 1975 Nov;112(5):657-711
references.pmid: 1103668
references.citation: J Microsc. 2008 Apr;230(Pt 1):84-93
references.pmid: 18387043
references.citation: J Appl Physiol (1985). 1994 Sep;77(3):1060-6
references.pmid: 7836104
references.citation: Dtsch Tierarztl Wochenschr. 1972 Dec 1;19(23):585-8
references.pmid: 4568479
references.citation: Respir Physiol. 1972 Mar;14(1):44-63
references.pmid: 5042157
references.citation: Mech Chem Biosyst. 2004 Mar;1(1):53-68
references.pmid: 16783946
references.citation: Respir Physiol. 1982 Feb;47(2):177-91
references.pmid: 6803317
references.citation: Am J Physiol Regul Integr Comp Physiol. 2001 Jul;281(1):R327-37
references.pmid: 11404309
references.citation: J Appl Physiol (1985). 1992 Apr;72(4):1473-9
references.pmid: 1592740
references.citation: Am J Physiol. 1985 Jul;249(1 Pt 2):R39-43
references.pmid: 4014495
references.citation: Med Hypotheses. 2000 Jul;55(1):36-9
references.pmid: 11021323
references.citation: J Biomech. 1999 Feb;32(2):183-8
references.pmid: 10052924
references.citation: Respir Physiol Neurobiol. 2010 Feb 28;170(2):202-9
references.pmid: 20038456
references.citation: Nature. 1963 Jan 5;197:54-6
references.pmid: 13980583
references.citation: Ergeb Anat Entwicklungsgesch. 1971;45(6):7-171
references.pmid: 4258755
references.citation: Anat Rec. 1997 Oct;249(2):213-25
references.pmid: 9335467
references.citation: Ann Anat. 1998 Aug;180(4):289-97
references.pmid: 9728268
references.citation: J Appl Physiol (1985). 1987 Sep;63(3):1185-94
references.pmid: 3654463
references.citation: Respir Physiol Neurobiol. 2006 May;152(1):115-8
references.pmid: 16431166
references.citation: Arch Histol Jpn. 1987 Dec;50(5):557-66
references.pmid: 3326543
references.citation: Respir Physiol. 1976 Feb;26(1):129-46
references.pmid: 1273386
references.citation: Environ Health Perspect. 1984 Apr;55:297-306
references.pmid: 6329673
references.citation: Physiol Rev. 1961 Apr;41:281-330
references.pmid: 13768766
references.citation: Int Rev Connect Tissue Res. 1968;4:283-348
references.pmid: 4880138
references.citation: Cell Tissue Res. 1977 Jan 24;176(4):553-64
references.pmid: 832311
references.citation: Philos Trans R Soc Lond B Biol Sci. 1989 Nov 30;326(1231):1-57
references.pmid: 2575769
references.citation: Pediatr Res. 1999 May;45(5 Pt 1):615-25
references.pmid: 10231854
references.citation: Am J Physiol Regul Integr Comp Physiol. 2009 Dec;297(6):R1625-34
references.pmid: 19793953
references.citation: Poult Sci. 2007 May;86(5):984-98
references.pmid: 17435037
references.citation: Respir Physiol. 1985 Jan;59(1):15-25
references.pmid: 3975499
references.citation: Osteoarthritis Cartilage. 1999 Jan;7(1):81-94
references.pmid: 10367017
references.citation: Respir Physiol Neurobiol. 2008 Feb 1;160(2):208-14
references.pmid: 17981521
references.citation: Respir Physiol Neurobiol. 2007 Jan 15;155(1):1-10
references.pmid: 16815758
references.citation: J Appl Physiol. 1969 Jan;26(1):65-76
references.pmid: 5762878
references.citation: Acta Anat (Basel). 1997;159(1):30-41
references.pmid: 9522895
references.citation: Respir Physiol Neurobiol. 2007 Nov 15;159(2):141-5; author reply 146
references.pmid: 17900998
references.citation: Biopolymers. 1979 Aug;18(8):2091-2103
references.pmid: 497355
references.citation: Am J Physiol Lung Cell Mol Physiol. 2007 Mar;292(3):L769-77
references.pmid: 17114279
references.citation: Baillieres Clin Rheumatol. 1988 Apr;2(1):1-36
references.pmid: 3046755
references.citation: J Histochem Cytochem. 1984 Feb;32(2):230-8
references.pmid: 6363520
references.citation: Arch Histol Cytol. 2004 Mar;67(1):31-40
references.pmid: 15125021
references.citation: Physiol Rev. 1973 Apr;53(2):419-95
references.pmid: 4581654
references.citation: Respir Physiol. 1981 Apr;44(1):61-86
references.pmid: 7232887
references.citation: Respir Physiol. 1969 Apr;6(3):298-308
references.pmid: 5778476
references.citation: Zoology (Jena). 2002;105(3):225-37
references.pmid: 16351871
references.citation: Eur Respir J. 2007 Jan;29(1):11-7
references.pmid: 17197481
references.citation: Z Mikrosk Anat Forsch. 1983;97(5):863-72
references.pmid: 6673392
references.citation: Circ Res. 1956 Jul;4(4):393-9
references.pmid: 13330181
references.citation: Arch Histol Cytol. 1992;55 Suppl:225-32
references.pmid: 1290671
references.citation: J Appl Physiol (1985). 1990 Aug;69(2):756-65
references.pmid: 2228886
references.citation: Respir Physiol. 1979 Sep;38(1):23-35
references.pmid: 515560
references.citation: Methods Cell Biol. 1980;21A:37-64
references.pmid: 6997687
references.citation: J Histochem Cytochem. 1988 Sep;36(9):1167-73
references.pmid: 3403967
references.citation: Respir Physiol Neurobiol. 2007 Aug 1;157(2-3):382-90
references.pmid: 17222589
references.citation: FEBS Lett. 2003 Jan 16;534(1-3):7-10
references.pmid: 12527354
references.citation: J Anat. 1982 May;134(Pt 3):553-62
references.pmid: 7107515
references.citation: Acta Anat (Basel). 1982;112(3):264-70
references.pmid: 7102251
references.citation: Am Rev Respir Dis. 1977 Mar;115(3):449-60
references.pmid: 851458
references.citation: Int Rev Connect Tissue Res. 1976;7:211-49
references.pmid: 770366
references.citation: Pediatrics. 2000 Dec;106(6):1452-9
references.pmid: 11099603
references.citation: J Exp Biol. 2001 Jul;204(Pt 13):2313-30
references.pmid: 11507114
references.citation: J Anat. 1969 Sep;105(Pt 2):323-36
references.pmid: 5802936
references.citation: Anat Rec. 1995 Sep;243(1):63-70
references.pmid: 8540633
references.citation: Rev Physiol Biochem Pharmacol. 1979;86:137-86
references.pmid: 386468
references.citation: J Appl Physiol (1985). 2005 Feb;98(2):672-9
references.pmid: 15448123
references.citation: Am Rev Respir Dis. 1975 Feb;111(2):184-8
references.pmid: 163067