Fine structure of the osteocyte capsule and of the wall of the lacunae in bone

Wassermann, F.; Yaeger, James A.

doi:10.1007/bf00340329

Cited by 79 publications

(19 citation statements)

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“…Although electron microscopy studies have suggested the existence of a pericellular structure in the canaliculi [1,21,22,27,30], there are no quantitative data on the fine structure of the pericellular matrix. The current study provides indirect evidence of the fiber spacing of the pericellular matrix in the lacunar-canalicular pores, and suggests that this pore size falls in the range of 6-10 nm in rat long bone, because reactive red (approximately 1 nm), microperoxidase (approximately 2 nm), and horse-radish peroxidase (approximately 6 nm) could pass through the lacunar-canalicular pores and reach osteocytic lacunae away from the blood vessels, while the 10-nm ferritin was excluded from the osteocyte population and was confined to the vascular canals.…”

Section: Discussionmentioning

confidence: 99%

“…Within the lacunar-canalicular channels, a gel-like fiber matrix with a fiber spacing of approximately 7 nm, similar to the surface glycocalyx on endothelial cells, has been proposed to fill the pericellular fluid space [5,26,28,31]. Although electron microscopy studies have suggested the existence of such a fiber matrix [1,21,22,27,30], the ultrastructure of the lacunar-canalicular porosity remains elusive. The smallest porosity, the collagen-apatite porosity (approximately 10-nm radius), has been postulated to form between apatite crystallites during the process of collagen mineralization.…”

Section: Introductionmentioning

confidence: 99%

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Delineating bone's interstitial fluid pathway in vivo

Wang

Ciani

Doty

et al. 2004

Bone

118

103

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Although interstitial fluid flow has been suggested to play a role in bone adaptation and metabolism, the constituents and ultrastructure of this interstitial fluid pathway are not well understood. Bone's lacunar-canalicular porosity is generally believed to be a continuous interstitial fluid pathway through which osteocytes sense external mechanical loading as well as obtain nutrients and dispose of wastes. Recent electron microscopy studies have suggested that a fiber matrix surrounds the osteocytic cell processes and fills this pericellular fluid space. However, studies injecting tracer molecules into the bone vasculature have provided conflicting results about the pore size or the fiber spacing of the interstitial fluid pathway. In addition, whether the smaller collagen-apatite porosity in adult bone is also a continuous fluid pathway is still unclear. To delineate bone's interstitial fluid pathway, four tracers of various size were injected into rats: reactive red (approximately 1 nm), microperoxidase (MP, approximately 2 nm), horseradish peroxidase (HRP, approximately 6 nm), and ferritin (approximately 10 nm). Five minutes after injection, the tibiae were harvested and processed using histological protocols optimized to minimize processing time to reduce possible redistribution of tracer molecules. The number of blood vessels and osteocytic lacunae labeled with the tracers per unit bone area was then measured for mid-diaphysial cross-sections of the tibia. While none of the tracers was detected within the mineralized bone matrix (the collagen-apatite porosity) using light microscopy, all the tracers except ferritin were found to pass through the canaliculi and appear in the osteocytic lacunae. These results indicate that while small tracers (< 6 nm) readily pass through the lacunarcanalicular porosity in the absence of mechanical loading, there appears to be an upper limit or cutoff size between 6 and 10 nm for molecular movement from bone capillaries to osteocytic lacunae in rat long bone. This range of pore size contains the most likely fiber spacing (approximately 7 nm) that has been proposed for the lacunar-canalicular annular space based on the presence of a proteoglycan fiber matrix surrounding the osteocyte.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Delineating bone's interstitial fluid pathway in vivo

Wang

Ciani

Doty

et al. 2004

Bone

118

103

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show abstract

“…The pericellular space between the osteocyte and lacunar wall can range between 0.1 and 2.7 lm, while in culture, osteocyte primary cilia are measured to be between 2 and 9 lm long [74,121]. This difference in pericellular space and length of primary cilia in vitro highlights the uncertainty in applying conclusions derived in vitro to how cilia function in vivo.…”

Section: Future Workmentioning

confidence: 95%

Primary Cilia-Mediated Mechanotransduction in Bone

Lee

Hoey

Jacobs

2010

Clinic Rev Bone Miner Metab

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Mechanotransduction is a process in which cells sense applied mechanical stimulus and convert these forces into biochemical responses. This process regulates skeletal homeostasis, organization, and development, although the cellular mechanism that is responsible for mechanotransduction in bone is currently unknown. One candidate mechanosensor is the primary cilium, a single immotile organelle that extends from the surface of bone cells. The inhibition of primary cilia formation or associated components leads to reduced expression of mechanosensitive osteogenic genes, impaired osteoblastic differentiation, and skeletal phenotype irregularities. In this review, we discuss growing evidence supporting primary cilia as mediators of mechanically regulated skeletal homeostasis and development.

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“…The presence of osteocytes creates a morphologically distinctive skeletal material with an extensive interconnected network of microscopic canals (canaliculi) associated with cell lacunae (Gray, 1941;Moss, 1961;Mjor, 1962;Wassermann and Yaeger, 1965;Cowin, 2007). Dendritic processes radiate from the osteocytes and project into these canals allowing for direct communication between the adjacent osteocytes and the external environment via gap junctions (Aarden et al, 1994;Donahue, 2000;Kusuzaki et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

The material properties of acellular bone in a teleost fish

Horton

Summers

2009

Journal of Experimental Biology

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SUMMARYSeveral lineages of teleost fishes have independently derived skeletons composed solely of acellular bone, a tissue without obvious advantages over bone that has osteocytes in the matrix. There is no consensus for the functional role of acellular bone, as factors such as salinity, activity level and gross morphology have been shown to be poor predictors of acellularity. We used a three-point bending method to test the hypothesis that the material stiffness (elastic modulus) of acellular bone is higher than that of cellular bone, which could be evidence that material properties were a selective pressure in the evolution of this unusual skeletal material. The acellular ribs of Myoxocephalus polyacanthocephalus are curved, hollow beams that decrease in size both distally and posteriorly along the rib series. First and second moments of area decreased distally and caudally in all individuals. Young's modulus (E) ranged from 3.67 to 8.40 GPa, with a mean of 6.48 GPa. The flexural stiffness (EI) differed significantly between ribs, and the hollow cylinder morphology increased the flexural stiffness by 12.0% over a solid, circular cross-section rod with the same area. Contrary to our expectations, acellular bone is not stiffer by virtue of fewer lacunae but instead falls at the very low end of the range of stiffness seen in cellular bone. There remains the possibility that other properties (e.g. fatigue resistance, toughness) are higher in acellular bone.

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Fine structure of the osteocyte capsule and of the wall of the lacunae in bone

Cited by 79 publications

References 19 publications

Delineating bone's interstitial fluid pathway in vivo

Delineating bone's interstitial fluid pathway in vivo

Primary Cilia-Mediated Mechanotransduction in Bone

The material properties of acellular bone in a teleost fish

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