title: Three-dimensional cortical bone microstructure in a rat model of hypoxia-induced growth retardation.
abstract: Little is known about hypoxia-induced modification of the canal network in the cortical bone despite its involvement in intracortical vascularity and bone blood supply. In this study, we examined the effect of chronic hypoxia on the canal network in postnatal bone. Tibiae were harvested from 4- and 8-week-old rats (hyp-4 and -8, n = 8 each), whose growth was retarded owing to postnatal exposure to hypoxia (12-14% O₂), and from 3- and 4-week-old normoxic rats (cnt-4 and -5, n = 8 each), which were similar in tibial length and cortical cross-sectional area to hyp-4 and -8, respectively. The diaphyseal canals were detected by monochromatic synchrotron radiation CT with a 3.1-μm voxel resolution. The anatomical properties of the canal network were compared between age- or size-matched hypoxic and normoxic groups. The canals were larger in diameter, were more densely distributed and connected, and opened into the marrow cavity with a higher density in hyp-4 than in cnt-4. The canal density and connectivity were also higher in hyp-4 than in cnt-3. The canal diameter, density, and connectivity were smaller in hyp-8 than in cnt-4; however, the densities of endocortical and periosteal canal openings did not differ between hyp-8 and cnt-4. We concluded that chronic hypoxia enhanced the formation of cortical canal networks at the postnatal developmental stage, probably facilitating intra- and transcortical vascularization and bone perfusion accordingly.
authors.affiliation: Bioengineering Division, Osaka University Graduate School of Engineering Science, Machikaneyama-cho 1-3, Toyonaka 560-8531, Japan. matsu@me.es.osaka-u.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Ando
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tomii
authors.forename: Kentaro
authors.initials: K
authors.lastname: Uesugi
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015519:Bone Density / Q000502:physiology; D001848:Bone Diseases, Developmental / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D001842:Bone and Bones / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology / Q000648:ultrastructure*; D003198:Computer Simulation; D004195:Disease Models, Animal; D006130:Growth Disorders / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000473:pathology; D000860:Hypoxia / Q000150:complications*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D017356:Synchrotrons; D054928:Validation Studies as Topic; D055114:X-Ray Microtomography