Location
Philadelphia, PA
Start Date
30-4-2025 1:00 PM
End Date
30-4-2025 4:00 PM
Description
Background and Rationale
Shifts in vertebral count and identity have occurred multiple times across mammalian evolution, including in primates. Understanding the development of the spine and the vertebrae that contribute to it is crucial for looking at changes in locomotor patterns in primates, such as bipedality in humans. During development, two halves of separate somites (the building blocks of vertebrae) contribute to one vertebra and each part is under different developmental regulation. In anthropology, individual characteristics like centrum height, articular facet shape, or spinous process shape are used to determine vertebral identity of fossil specimens, typically without consideration of the underlying development. Therefore, it is important to determine features that may be developmentally linked or independent.
Hypothesis
Since different somites contribute to the centrum and spinous process and articular facets, we hypothesize that when there is a shift in transitional vertebra, placement height and width of the centrum will be unmodified while the spinous process will modify. Genetic modification of Hox9 in mice results in the correlated modification of spinous process shape and placement of the transitional vertebra independent of alternation in lumbar number, mimicking changes observed in hominoids.
Methods
3DSlicer was used to assess morphological differences in the vertebrae across the thoracolumbar transition of mice with Hox9 gene modifications compared to wild type C57Blk6 mice. Centrum thickness, centrum height, and cranial and caudal angle measurements were taken from microCT scans by two independent observers. Changes in the appearance of the spinous process were noted separately, with a particular focus on vertebrae T10 and T11. Data were analyzed using the articular facet definition based on where the facet changes from coronal to sagittal orientation.
Results
In mice with a Hoxc9 allele knocked out, we observed a corresponding shift in spinous process angle, articular facet shape, and anterior/posterior centrum width. Cranial/caudal centrum height was independent of articular facet shape. These results partially support our hypothesis and indicate that the centrum may have contribution from two somites.
Significance
These results indicate that centrum height may not be a complete indicator of vertebral identity and location of the transitional vertebra.
Embargo Period
5-29-2027
Thoracolumbar Vertebral Morphology in Hox9 Mice
Philadelphia, PA
Background and Rationale
Shifts in vertebral count and identity have occurred multiple times across mammalian evolution, including in primates. Understanding the development of the spine and the vertebrae that contribute to it is crucial for looking at changes in locomotor patterns in primates, such as bipedality in humans. During development, two halves of separate somites (the building blocks of vertebrae) contribute to one vertebra and each part is under different developmental regulation. In anthropology, individual characteristics like centrum height, articular facet shape, or spinous process shape are used to determine vertebral identity of fossil specimens, typically without consideration of the underlying development. Therefore, it is important to determine features that may be developmentally linked or independent.
Hypothesis
Since different somites contribute to the centrum and spinous process and articular facets, we hypothesize that when there is a shift in transitional vertebra, placement height and width of the centrum will be unmodified while the spinous process will modify. Genetic modification of Hox9 in mice results in the correlated modification of spinous process shape and placement of the transitional vertebra independent of alternation in lumbar number, mimicking changes observed in hominoids.
Methods
3DSlicer was used to assess morphological differences in the vertebrae across the thoracolumbar transition of mice with Hox9 gene modifications compared to wild type C57Blk6 mice. Centrum thickness, centrum height, and cranial and caudal angle measurements were taken from microCT scans by two independent observers. Changes in the appearance of the spinous process were noted separately, with a particular focus on vertebrae T10 and T11. Data were analyzed using the articular facet definition based on where the facet changes from coronal to sagittal orientation.
Results
In mice with a Hoxc9 allele knocked out, we observed a corresponding shift in spinous process angle, articular facet shape, and anterior/posterior centrum width. Cranial/caudal centrum height was independent of articular facet shape. These results partially support our hypothesis and indicate that the centrum may have contribution from two somites.
Significance
These results indicate that centrum height may not be a complete indicator of vertebral identity and location of the transitional vertebra.