Doctoral Dissertation Improvement: Histomorphometry of the Endosteal Lamellar Pocket: Comparing Modeling Drift Remnants Among Several Archaeological and Modern Skeletal Populations

Ohio State University, The, Columbus OH

Investigators

Abstract

This research furthers our understanding of bone growth processes, permitting new, hypothesis driven testing of basic skeletal histology. The results have direct impact on histological age estimation, micro-site trace-element and stable-isotopic analyses, and understanding mechanical adaptation and the adolescent growth spurt. New micro-photographic techniques and custom software applications are introduced that permit accurate quantification of subjective features, useful in many other fields. In addition to providing equipment and technical knowledge benefiting students, volunteers, and lab technicians at sites of research, the project strengthens existing cooperation between local and international research institutions. Yearly invited presentations and workshops, a Spanish language newsletter available to the community, and professional publications have kept, and will continue to keep students at each participating institution informed regarding the project as well as future collaborative opportunities. Diametric growth of long bones occurs along membrane-covered, inner and outer surfaces. The process requires bone formation, the sequential stratigraphy of which provides a record of growth magnitude and direction and ultimately results in increased thickness. However, growth and mechanical adaptation at these membranes also requires significant resorption, removing tissue to form and maintain bone shape and ensuring proper positioning of the internal cavity over time. Thickness and shape are two major determinants of bone strength and can reveal important information about an individual's growth and adaptation to mechanical strain. Unfortunately no replicable, accurate technique is currently available to quantify the direction(s) of bone diametric growth over time, so only part of how a bone achieved its current position, size, and shape is known. This research uses polarizing microscopic, familiar point-count, and custom computerized image-analysis to emphasize and measure predictable patterns of asymmetry in diametric growth (modeling drift). These patterns are combined as a metafeature of the bone's inner margin, called the endosteal lamellar pocket (ELP), indicating the bone's net drift direction and can be compared between bones, individuals, and populations. Results will alter the way boney response during growth and mechanical adaptation are considered, permitting new, testable hypotheses in bone biology and bioarchaeology. Potential novel applications include micro-site stable isotopic analysis, allowing dietary examination at fine resolution across years of bone deposition; augmentation of current age estimation techniques; and new optical variables complimenting cross-sectional geometric assessment of physical activity patterns.