Long bone maturation is driven by pore closing: A quantitative tomography investigation of structural formation in young C57BL/6 mice.
During mammalian growth, long bones undergo extensive structural reorganization, transforming from primitive shapes in the limb buds into mature bones. Here we shed light on the steps involved in structural formation of the mineralized tissue in midshafts of C57BL/6 femurs, shortly after birth. By combining 3D micrometer-resolution X-ray microtomography with 2D histology, we study the transformation of the tissue from a partially-mineralized scaffold into a compact bone structure. We identify three growth phases that take place during murine long bone maturation: During a patterning phase (I) mineralized struts form a loosely connected foam-like cortical network. During a transitioning phase (II), the extensive non-mineralized tracts vanish, transforming the foam into a fully continuous mass, by 14 days of age. Concomitantly, closed porosity increases to about ∼ 1.4%, and stays at this level, also found in maturity. During a shaping phase (III), the bones gradually attain their characteristic intricate adult form. Architectured mineral depositioning--first in open foamy scaffolds, and later into solid bone material--is presumably a compromise between the mechanical needs of providing support to the body, and the biological requirements of vascularization and extensive nutritional needs in the early stages of bone formation.
['Bortel|Emely L|EL|', 'Duda|Georg N|GN|', 'Mundlos|Stefan|S|', 'Willie|Bettina M|BM|', 'Fratzl|Peter|P|', 'Zaslansky|Paul|P|']
D000818:Animals D001846:Bone Development D001842:Bone and Bones D002113:Calcification, Physiologic D005269:Femur D021621:Imaging, Three-Dimensional D008810:Mice, Inbred C57BL D016062:Porosity D015203:Reproducibility of Results D055114:X-Ray Microtomography
Bone Histomorphometry Microstructure Organogenesis Osteogenic patterning