Abstract: Osteocytes, the most prevalent cell type in bone, appear to communicate via gap junctions. In limb-bone diaphyses, it has been hypothesized that these cellular networks have the capacity to monitor habitual strains, which can differ significantly between cortical locations of the same bone. Regional differences in microdamage associated with prevalent/predominant strain mode (tension, compression, or shear) and/or magnitude may represent an important "variable" detected by this network. This hypothesis was indirectly addressed by examining bones subjected to habitual bending for correlations of osteocyte lacuna population densities (n/mm(2) bone area, Ot.Lc.N/B.Ar) with locations experiencing high and low strain, and/or prevalent/predominant tension, compression, and shear. We examined dorsal ("compression"), plantar ("tension"), and medial/lateral ("shear" or neutral axis) cortices of mid-diaphyseal sections of calcanei of adult sheep, elk, and horses. Ot.Lc.N/B.Ar data, quantified in backscattered electron images, were also evaluated in a context of various additional structural and material variables (e.g. % ash, cortical thickness, porosity, and secondary osteon population). Results showed significant differences in dorsal versus plantar comparisons with the highest Ot.Lc.N/B.Ar in dorsal cortices of sheep and elk (p < 0.0001); but this was a statistical trend in the equine calcanei (p = 0.14). There were no consistent transcortical (pericortical to endocortical) differences, and Ot.Lc.N/B.Ar in neutral axes was not consistently different from dorsal/plantar cortices. Correlations of Ot.Lc.N/B.Ar with structural and material parameters were also poor and/or inconsistent within or between species. These results provide little or no evidence that the number of osteocyte lacunae has a functional role in mechanotransduction pathways that are typically considered in bone adaptation. Although dorsal/plantar differences may be adaptations for prevalent/predominant strain modes and/or associated microdamage, it is also plausible that they are strongly influenced by differences in the bone formation rates that produced the tissue in these locations.
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The research article explores osteocyte density in different species and their potential roles in bone adaptation and strain management. The study focused on bones in sheep, elk and horses, but found little evidence that osteocyte density contributes to these processes.
Research Methodology
The study examines osteocyte lacuna population densities in the calcanei (heel bones) of adult sheep, elk, and horses. These species were subjects as their heel bones are subject to habitual bending.
The researchers looked into the different areas of the bones where tension, compression, and shear (or neutral) strains are experienced.
They used backscattered electron images to quantify osteocyte lacuna population densities (Ot.Lc.N/B.Ar).
In addition, structural and material variables were evaluated. These included percentage of ash, cortical thickness, porosity, and population of secondary osteons.
Findings
The dorsal cortices (deemed “compression” regions) of the sheep and elk demonstrated the highest osteocyte densities, but this was not a significant finding in the horses.
There were no consistent differences across the bones’ cortex (pericortical to endocortical), and the middle or ‘neutral’ regions did not consistently differ from dorsal or plantar cortices.
Poor or inconsistent correlations were observed between osteocyte density and the structural and material parameters in or across the species.
Conclusions
The results found limited evidence that the number of osteocyte lacunae plays a role in the mechanotransduction pathways typically considered in bone adaptation.
While the differences in the density of osteocytes may be adaptations for various strain modes and associated with microdamage, it is plausible they might be more related to differences in bone formation rates in those specific areas.
Cite This Article
APA
Skedros JG.
(2006).
Osteocyte lacuna population densities in sheep, elk and horse calcanei.
Cells Tissues Organs, 181(1), 23-37.
https://doi.org/10.1159/000089966
Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT 84107, USA. jskedros@utahboneandjoint.com
MeSH Terms
Analysis of Variance
Animals
Bone Density
Calcaneus / cytology
Calcaneus / metabolism
Calcaneus / physiology
Deer / anatomy & histology
Deer / physiology
Female
Horses / anatomy & histology
Horses / physiology
Imaging, Three-Dimensional
Male
Osteocytes / physiology
Sheep / anatomy & histology
Sheep / physiology
Citations
This article has been cited 4 times.
Shah FA, Ruscsák K, Palmquist A. 50 years of scanning electron microscopy of bone-a comprehensive overview of the important discoveries made and insights gained into bone material properties in health, disease, and taphonomy. Bone Res 2019;7:15.
Carter Y, Suchorab JL, Thomas CD, Clement JG, Cooper DM. Normal variation in cortical osteocyte lacunar parameters in healthy young males. J Anat 2014 Sep;225(3):328-36.
Skedros JG, Clark GC, Sorenson SM, Taylor KW, Qiu S. Analysis of the effect of osteon diameter on the potential relationship of osteocyte lacuna density and osteon wall thickness. Anat Rec (Hoboken) 2011 Sep;294(9):1472-85.
Skedros JG. A 50-year perspective on the use and potential of artiodactyl calcanei in bone adaptation studies. Biol Rev Camb Philos Soc 2026 Feb;101(1):437-485.