Microscopic Examination

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With sections prestained with MIBS, osteoid seams appear as dark red, magenta, or green, while mineralized bone is unstained. Under ultraviolet light illumination, the two fluorescent labels and osteoid seams are bright yellow, golden yellow and bright red, respectively. Eroded surfaces (ES) are identified by scalloped irregularities in the surfaces of cancellous bone. Frequently osteoclasts occupies these scalloped excavations

Cement lines (reversal lines) are identified by their dark purple staining patterns with the gallocyanin stain.

Osteoblasts are classified as cuboidal, columnar, or ovoid shape with an adjacent juxtanuclear vacuoles or nuclear clear zone. The majority of these cells lay perpendicular to or lining the intima of the osteoid surface.

Calculations


All calculations, symbols, and abbreviations are derived from the American Society for Bone and Mineral Research Histomorphometry Committee (Parfitt et al. 1987). The definitions and descriptions are described below:

Volume data

Measurement Units Description
Bone volume (BV/TV) % Total area of cancellous bone (mineralized bone and osteoid in the section expressed as percentage of total area (TtAr)
Mineralized volume (MdV/TV) % Mineralized area (MdAr) minus osteoid area (OSAr) in the section expressed as percentage of total area (TtAr)
Osteoid volume(OV/TV) % Total area of osteoid tissue in the section expressed as percentage of total area of mineralized bone plus osteoid
Osteoid volume(OV/BV) % Total area of osteoid tissue in the section expressed as percentage of mineralized bone.

Primary Data

Measurement Units Description
Trabecular thickness
(TbTh)
µ Estimated indirectly as twice the area to perimeter ratio times π/4
Trabecular separation
(TbSp)
µm Distance between edges of cancellous bone, calculated as TbTh (TV/BV-1)
Trabecular number
(TbN)
#/mm Derived from formula: BV/TV x 10/TbTh
Wall thickness
(WTh)
µm Mean distance between nearest reversal line (cement line) and bone marrow interface at any quiescent surface
Osteoid thickness
(Oth)
µ Distance between the osteoid/bone interface and osteoid/marrow interface
Osteoid surface
(OS)
mm Perimeter or length of osteoid seams in a given cancellous bone surface
Erosion surface
(ER)
mm Perimeter or length of erosion lacuna in a given cancellous bone surface
Cuboidal osteoblasts
(CuOb)
mm Total length of cuboidal osteoblasts adjacent to an osteoid seam
Osteoclasts
(Oc)
mm Total length of osteoclasts adjacent to an erosion lacuna

Surface Data

Measurement Units Description
Osteoid surface
(OS/BS)
% Total perimeter or length of osteoid seams expressed as percentage of total cancellous bone perimeter
Eroded surface
(ER/BS)
% Total erosion lacunar surface expressed as percentage of total cancellous bone surface
Osteoblast’s surface
(ObS/BS)
% Total perimeter or length of adjacent “active” osteoblasts (cuboidal, columnar, or ovoid osteoblasts) expressed as percentage of total cancellous bone surface (BS) or osteoid surface (OS)
Osteoclast’s surface
(OcS/BS)
% Total length of adjacent osteoclasts expressed as percentage of total cancellous bone surface
Osteoclast’s surface
(OcS/NOS)
% Total length of adjacent osteoclasts expressed as percentage of total cancellous bone surface minus osteoid surface
Mineralizing surface
(MS/BS)
% Total length of double labels plus ½ single labels adjacent to osteoid seams expressed as percentage of total cancellous bone surface
Mineralizing surface
(MS/OS)
% Total length of double labels plus ½ single labels adjacent to osteoid seams expressed as percentage of total osteoid surface

Dynamic Data

Measurement Units Description
Mineral apposition rate
(MAR)
mcm/day Mean distance between midpoints of two fluorescent markers divided by number of days between them
Adjusted apposition rate
(AjAR)
mcm/day Mineral apposition rate multiplied by mineralizing surface (MS/OS, %) averaged over entire osteoid surface; rate of advance of demarcation zone averaged over entire osteoid seam surface
Osteoid maturation time
(Omt)
Days Mean osteoid thickness divided by mineral apposition rate
Mineralization lag Time
(Mt)
Days Period between first appearance of new osteoid moiety and its mineralization; equals time required for demarcation zone to advance a distance equal to osteoid thickness; calculated by dividing osteoid thickness by adjusted apposition rate
Formation period (FP)
(also known as sigma-f (of)
Days Calculated as mean wall thickness divided by adjusted apposition rate (AjAR, µm/day); equals time required for demarcation zone to advance a distance to mean wall thickness
Bone formation rate, surface referent
(BFR/BS)
µm³µm²/ year Total surface referent signifying how many µm³ of new bone made on each µm² cancellous bone surface each year
Bone formation rate, volume referent
(BFR/BV)
%/year Total volume referent signifying how many µm³ of new bone is made on each µm³ of existing bone expressed as percent per year; equivalent for fractional turnover rate.
Bone formation rate, tissue referent
(BFR/TV)
%/year Total tissue referent signifying how many µm³ of new bone is made per µm³ of total tissue expressed as percent per year.

References

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