Biology 1615

            Projections that serve for tendon and ligament insertion or articulation that are located on long bones are called super structures. The location and position of this projection along the bone is critical for the functionality of the musculoskeletal system. During one intense research study, scientists were trying to determine how these superstructure positions are regulated during all stages of growth to end up in the correct spots. Elongating only from their ends, mysterious rigid bones have left us all wondering just how their positions are regulated during growth to wind up correctly after development. It was originally understood that while humans develop, the superstructures continuously relocate, or drift, along the shaft as they are also reconstructed in the meantime. Using specialized methods including capturing three-dimensional images of rodents, isometric scaling, and meticulous logarithmic formulas, only then were they able to determine a conclusion.

            Using hundreds of three-dimensional micro-CT images of developing long bones in various male mice enabled scientists to analyze the precise measurements and change of place. Harlan Laboratories, located in Jerusalem, begun the experiment by first gathering all male mice to evaluate. The embryos were removed from the mother, followed by the uterus being suspended in a cold phosphate-buffered saline. They then harvested and dehydrated the soon-to-be-measured limbs overnight in a specific sequence in order to avoid overly rapid reaction rates. Once limbs were acquired for observation, several bones were scanned using an iodine contrast agent to create the visibility of cartilaginous tissue. This process was used to analyze the distribution of symmetry-breaking elements along the shaft of the bone. Another set of mice was scanned, receiving measurements of the tibia and fibula. Next, an x-ray microscope was used to measure relative and physical positions and the growth rates on a third set of mice. Approximately six to eight of these mice at every developmental stage prior to P4 were closely assessed. Once they were to reach P6, two to four rodents were evaluated from separate litters.

             Results sharply indicated isometric scaling. In other words, the relative position of the superstructure does not drift at all; instead, our bones show a unique balance in growth between distal and proximal ends. The synchronization between growth balance and element drifting patterns achieves this isometric scaling. In order to optimize the scaling process, these researchers show a mathematical equation that accurately measures superstructure position relative to the ends of the bones. These results show us that as we develop and our bones begin to lengthen during childhood, the projections on our long bones used for tendon and ligament insertion grow isometrically, or evenly, rather than undergoing constant change.

                 This research study was exceptionally detailed and intriguing, although I do not agree with their approach. Working to obtain all of the bones needed for gauging, they wrongly impregnated living animals with the sole purpose to dissect the uterus out of the mother and manipulate it. As stated in the research article, “embryos and postnatal mice were sacrificed by decapitation with surgical scissors,” which attests that the ethical viewpoint of these procedures was awfully inhumane. I would have liked to see them measure human long bones in the developing fetus using these three-dimensional image scanners, therefore causing no harm and ensuring there are no developmental differences between the two species. Perhaps a study proving the correspondences between maturation stages of both rodent bones and human bones would be interesting and would supplement as backing to their theory. After further searching, I was unable to find any credible related articles to use as a comparison. Hopefully this discovery will lead to further studies and further findings that can be useful in medicine.

                    The findings of this research can be beneficial in the understanding of some physical abnormalities in newborns. By recognizing the balanced course of long bone lengthening, doctors can better understand possible causes or flaws in unfortunate cases. If a baby happens to be born prematurely, we can also conclude that their superstructures—such as the visible ones we have located on our inner and outer ankles—are undeniably situated on an accurate site, given the facts. As I plan to continue to my schooling in the field of Sports Medicine, I’m confident that I will one day be able to reflect on this data as guidance to a missing puzzle piece.