NANOINDENTATION OF BONE - Nanoindentation with Biological Applications - page 218

4.1. Nanoindentation, quantitative histomorphometry, and
rodent models
Histology and histomorphometry provide valuable information about the
location and quantity of bone. Quantitative histomorphometry of bone,
with a well-defined nomenclature, 154 provides quantitative analysis at the
microscopic level of cellular activities ( e.g. , mineral apposition rate)
and bone geometry. Dynamic histomorphometry involves the use of
florescent labels, e.g. , tetracycline or calcein green, to provide in vivo
labeling of the skeleton at specific time-points for quantitative
measurements of new bone formation ( Fig. 7-5 ) .
In mice and rats, the use of florescent labels is common as it enables
the assessment of bone metabolism within times ranging from hours to
weeks. Mice offer multiple advantages such as rapid bone growth, low
cost, small size which allows large sample numbers, and a wide range of
transgenic/knockout possibilities to study health and disease. 155 The use
Figure 7-5. Cross-section of a mouse femur treated with bone anabolic therapies. 158
Florescent labels (showing as bright lines within the bone tissue and parallel to the bone
surfaces) were administered on specific days during the study to mark new bone
formation. Extant, or existing, bone lies “outside” of the labeled areas. Indentations were
placed across regions of extant and newly-formed bone to enable comparison of untreated
and treated tissue. Field Width = 2 mm.