Computations and Abbreviations for Bone Histomorphometry - Expanded
In Bone Histomorphometry: Standardization of Nomenclature, Symbols, and Units, Parfitt and colleagues cataloged and standardized the various derivative computations used in bone histomorphometry. An update of the standard nomenclature by Dempster and colleagues was published in late 2012 which introduced additional computations. As the discipline has expanded, additional terms were needed that do not appear in either the original publications or the 2012 update.
In addition to the standard nomenclature, the publications provide canonical computational formulas and definitions for histomorphometric indices. These are provided below the table of abbreviations.
This expanded version is based on the revised table from the 2012 update and is maintained by BIOQUANT to document computations used in our analysis templates. Any non-canonical terms and notes added by BIOQUANT are indicated in bold type.
Standardized Abbreviations Used in BIOQUANT OSTEO
A - L
- Apposition, Appositional
- Area (2D)b
- Active, Activity
- Basic Multicellular Unit
- Boundary (2D)b
- Canal, Canalicula, Canalicular
- Cytoplasm, Cytoplasmic
- Cortex, Cortical
- Dimension, Dimensional
- Differentiating, Differentiation
- Degenerative, Degeneration
- Diaphysis, Diaphyseal
- Eroded, Erosion
- Epiphysis, Epiphyseal
- Endosteal, Endosteumd
- Fat, Fatty
- Fibrosis, Fibrous
- Growth, Growing
- Interfacef (3D)b
- Label, Labeled
- Lacuna, Lacunarg
- Lamella, Lamellar
M - Z
- Mineral, Mineralizing, Mineralization
- Mononuclear, Mononucleated
- Metaphysis, Metaphyseal
- Multinuclear, Multinucleated
- Number of profiles or structures
- Number of sampling unitsh
- Osteoblast, Osteoblastic
- Osteoclast, Osteoclastic
- Osteon, Osteonal
- Osteocyte, Osteocytic
- Perimeter (2D)b
- Pore, Porous, Porosity
- Proliferating, Proliferative
- Periosteal, Periosteum
- Radial, Radius
- Reference, Referent
- Surface (3D)b
- Structure, Structural
- Trabecula, Trabeculari
- Thickness (3D)b
- Terminal, Terminus
- Volume (3D)b
- Width (2D)b
Standard Units and Formulas in Rodent Histomorphometry
- TV (Tissue Volume) mm2
The total area within the region of interest. Primary data are collected in μm2.
- BV (Bone Volume) mm2
The total area of bone, both mineralized bone and osteoid within the tissue volume. Primary data are collected in μm2.
- BV/TV %
Bone Volume normalized by Tissue Volume.
- BS (Bone Surface) mm
The total perimeter of the bone within the Tissue Volume. Does not include the surface segements where the bone crosses out of the Tissue Volume. Primary data are collected in μm.
- BS/BV mm-1
Bone Surface normalized by Bone Volume. The ratio of surface area to volume of a structure is known as specific surface area. Spheres have the lowest surface area to volume ratio. Highly irregular and complex structures generally have a higher surface area to volume ratio. Read more at the Wikipedia.
- Tb.Dm (Trabecular Diameter) mm
Tb.Dm = 4*(BV/BS).
- Tb.N (Trabecular Number) mm-1
Tb.N = SQRT(4/3.141*BV/TV)*(1/Tb.Dm). Rod Model.
- Tb.Sp (Trabecular Spacing) mm
Tb.Sp = (SQRT(3.141/4*TV/BV)-1)*Tb.Dm. Rod model.
- Ob.N/BS #/mm
Number of Osteoblasts per unit of Bone Surface.
- Ob.S/BS %
Osteoblast Surface as a Percentage of Bone Surface.
- O.Wi μm
The mean of all osteoid seam widths in the animal. Widths are measured perpendicularly at regular intervals along the surface. Primary data are collected in μm.
- Oc.S (Osteoclast Surface) mm
The length of bone surface occupied by the osteoclast. Primary data are collected in μm.
- Oc.N (Osteoclast Number) #
Number of osteoclasts is equal to the number of osteoclast surface measurements.
- Oc.N/BS #/mm
Number of Osteoclasts per millimeter of Bone Surface.
- Oc.S/BS %
Osteoclast Surface normalized by Bone Surface.
- sLS (Single Labeled Surface) mm
Bone surfaces with a single fluorescent label present. Primary data are collected in μm.
- dLS (Double Labeled Surface) mm
Bone surfaces with two fluorescent labels present. Primary data are collected in μm.
- MS (Mineralizing Surface) mm
MS = sLS/2+dLS.l
- Ir.L.Wi (Interlabel Width) μm
The mean of all direct measurements of distance between labels in double labeled surfaces. Distances are measured perpendicularly at regular intervals along the surface. Primary data are in collected μm.
- Ir.L.t (Interlabel Time) days
The time between injections used to label the mineralizing surfaces.
- MAR (Mineral Apposition Rate) μm/day
MAR = Ir.L.Wi/Ir.L.t.
- Aj.AR (Adjusted Apposition Rate) μm/day
If MS/OS < 1, then Aj.Ar = MAR*MS/OS. If MS/OS > 1, Aj.Ar = MAR.
- BFR/BS (Bone Formation Rate, Normalized by Bone Surface) μm/day
BFR/BS = MAR*MS/BS.
- BFR/BV (Bone Formation Rate, Normalized by Bone Volume) (μm/day)/mm
BFR/BV = MAR*MS/BV.
- BFR/TV (Bone Formation Rate, Normalized by Tissue Volume) (μm/day)/mm
BFR/TV = MAR\*MS/TV.
- Omt (Osteoid Maturation Time) days
A Note about Dimensionality in Naming Conventions
Primary bone data collected from histology is either area (two dimensional), length (one dimensional), or number ( zero dimensional) data. Yet, final histomorphometry data are usually reported in terms of volume (three dimensional), surface (two dimensional), and number (still zero dimensional). This tradition comes from a few equations in the field of "stereology," the study of statistical methods to analyze three dimensional structures from a limited number of two dimensional sections.
For example, the Delesse Principle holds that B.Ar/T.Ar is proportional to BV/TV. (The bone area to tissue area ratio in a section is proportional to the bone volume to tissue volume ratio in the whole trabecular compartment.) Therefore, it might be more accurate to name primary data arrays in BIOQUANT using area and perimeter (B.Ar, B.Pm), and to name computed arrays using volume ans surface (BV, BS). Certainly the nomenclature committee allows for this and provides the necessary abbreviations. In practice, however, this proved counter-intuitive.
BIOQUANT decided to use the volume, surface, and number terminology for both primary data and computed data. This consistency of naming makes it easy to track data through their various computations. Combined with clear labeling of units, this seems to balance the needs of conceptual clarity and computational accuracy.
A Note on the Various Abbreviations for Microns
In BIOQUANT, primary data are collected in calibrated units, normally microns (μm) and square microns (μm2). The ASBMR nomenclature committee reports uses the abbreviation mcm to refer to microns. BIOQUANT uses the mcm convention in its unit labels to maintain consistency with the nomenclature committee.
a Included here because of rekindled interest in assessing adipocyte parameters in the marrow space of iliac crest bone biopsies and the shared progenitor cell with osteoblasts.
b 2D or 3D refers to the format in which data are reported, not the dimensions of an individual quantity.
c Also day, but context should eliminate ambiguity.
d endocortical + cancellous
e As a process, not as a morphologic feature.
f Between osteoid and mineralized bone.
g If unqualified, osteocytic, not Howship's
h For example, subjects, sites, sections, etc.
i An individual structure, not a type of tissue.
j The 2012 update specifically mentions that, in the context of bone biology, the term density should be, "restricted to as far as possible to its primary meaning in physics of mass per unit volume, with a subsidiary meaning analogous to population density, which is applied mainly to cells."
k As a morphologic feature, not as a process.
l The logic here is that MS is the amount of surface of the bone that was mineralizing over the entire labeling period. The assumption is that some of the single label was active at the beginning of the period and some at the end. Labeling with once with calcein and once with alizarin red instead of calcein twice could help sort out this question. But, in general, labs just use calcein and say that half the single label was active at the beginning and half as active at the end. Hence, sLS/2 is the amount of single labeled surface that was active for the whole period.
Bone Histomorphometry: Standardization of Nomenclature, Symbols, and Units: Report of the ASBMR histomorphometry nomenclature committee. Parfitt et al. Journal of Bone and Mineral Research. Volume 2. Number 6. 1987.
Standardized Nomenclature, Symbols, and Units for Bone Histomorphometry: A 2012 Update of the Report of the ASBMR Histomorphometry Nomenclature Committee. Dempster et al. Journal of Bone and Mineral Research. Volume 28. Number 1. 2013.