Osteocyte size, shape, orientation, and population density

Summary

Despite being encased in lacunae, osteocytes are extensively interconnected and have several mechanisms that enable them to physically and chemically appraise their environment and adjust to it. In the perspective that cell-cell and cell-matrix interactions mediate these functions and are critically important during the formation of a mechanically competent bone organ, we focus on several considerations: (1) osteocyte lacunae are not always occupied by living cells and the percent lacuna vacancy can increase with aging, some diseases, and experimental perturbations, (2) the potential for the population density and/or sizes and shapes of osteocytes (or of their lacunae) and of their cell processes (typically seen as the canaliculi in which they reside) in helping investigators interpret the load history of a bone or bone region, and (3) scaling relationships between osteocyte density and various parameters, including animal mass and metabolism. We also point out that all of these considerations are being impacted by high-resolution three-dimensional imaging technologies that allow increased accuracy when quantifying details of lacunar-canalicular geometries.

Zusammenfassung

Auch wenn sie in Lakunen eingebettet sind, sind Osteozyten umfangreich verschaltet und verfügen über eine Vielzahl von Mechanismen, die es ihnen ermöglicht, ihre Umgebung in physikalischer und chemischer Hinsicht zu erkunden und sich den Gegebenheiten anzupassen. Unter dem Blickwinkel betrachtet, dass diese Funktionen über Zell-Zell- und Zell-Matrix-Interaktionen vermittelt werden und von besonderer Bedeutung für die Bildung eines mechanisch kompetenten Knochens sind, konzentrieren wir uns auf verschiedene Betrachtungen: (1) Nicht alle Osteozytenlakunen sind von Osteozyten besiedelt und der Anteil leerer Lakunen kann im Alter sowie durch Krankheit und experimentelle Pertubationen zunehmen, (2) das Potenzial für die Zelldichte und/oder Größe und Form der Osteozyten (oder ihrer Lakunen) und ihrer Zellprozesse (typischerweise als Kanalikuli betrachtet), die den Forschern dabei helfen, die Belastungsart eines Knochens und einer Knochenregion zu interpretieren, und (3) die Skalierungsbeziehung zwischen der Osteozytendichte und verschiedenen Parametern, einschließlich Tiergewicht und Stoffwechsel. Wir zeigen außerdem auf, dass alle diese Betrachtungen durch hochauflösende 3D-Bildgebungsverfahren beeinflusst werden, da diese eine höhere Genauigkeit bei der Quantifizierung von Einzelheiten der lakuno-kanalikunären Geometrie erlauben.

Keywords

Osteocyte - osteocyte lacuna - canaliculi - osteons - osteon morphotypes - bone

Schlüsselwörter

Osteozyt - Osteozytenlakunen - Kanalikuli - Osteone - Osteon-Morphotypen - Knochen

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