title: Setup of a bone aging experimental model in the rabbit comparing changes in cortical and trabecular bone: Morphological and morphometric study in the femur.
abstract: Bone aging was studied in an experimental model (rabbit femur) in three populations aged 0.5, 1.5, and 7.5 years. Cortical bone histology was compared with a data set from a 1.5-month-old population of an earlier published paper. From 0.5-year-old onward, the mean femur length did not increase further. Thereafter, the mean marrow area increased and the cortical area decreased significantly with aging. This was associated with a structural pattern transformation from plexiform to laminar and then Haversian-like type. The distal meta-epiphysis bone trabecular density of the oldest populations also was significantly lower in specific regions of interest (ROI). Percentage sealed primary vascular canals in laminar bone significantly increased with aging without variation of percentage sealed secondary osteons. Remodeling rate reflected by the density of cutting cones did not significantly change among the age populations. These data suggest that laminar bone vascular pattern is more functional in the fast diaphyseal expansion but not much streamlined with the renewal of blood flow during secondary remodeling. Bone aging was characterized by: 1) secondary remodeling subendosteally; 2) increment of sealed primary vascular canals number; 3) increased calcium content of the cortex; 4) cortical and trabecular bone mass loss in specific ROIs. Taken together, the present data may give a morphological and morphometric basis to perform comparative studies on experimental models of osteoporosis in the rabbit.
authors.affiliation: Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy.
authors.forename: Ugo E
authors.initials: UE
authors.lastname: Pazzaglia
authors.affiliation: Department of Medical Biotechnology and Translational Medicine, University of Milan, Milano, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Sibilia
authors.affiliation: Department of Surgical and Morphological Sciences, University of Insubria, Varese, Italy.
authors.forename: Terenzio
authors.initials: T
authors.lastname: Congiu
authors.affiliation: Department of Medical Biotechnology and Translational Medicine, University of Milan, Milano, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Pagani
authors.affiliation: Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Ravanelli
authors.affiliation: Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, University of Brescia, Brescia, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Zarattini
mesh_terms: D000375:Aging; D000818:Animals; D016723:Bone Remodeling; D001842:Bone and Bones / Q000033:anatomy & histology / Q000502:physiology*; D005269:Femur / Q000033:anatomy & histology; D006253:Haversian System; D008297:Male; D023421:Models, Animal; D011817:Rabbits / Q000502:physiology*
keywords: bone aging; bone modeling and remodeling; cortical bone; femur growth and morphometry; trabecular bone