Micro-CT examination of the primate cranial morphospace allows scientists to explore developmental, evolutionary, and functional influences that have contributed to primate cranial diversity. The primate cranium is quite complex, supporting vital functions such as respiration, olfaction, food acquisition and mastication, communication, and protection of the brain and eyes. Natural selection within different primate groups has produced variations that have resulted in a diversity of primate cranial forms.
Our example is of a skull from a six year old female common marmoset (Callithrix jacchus). Marmosets are the smallest of all monkey species and among the most primitive in terms of evolution. They do not have opposable thumbs, have claws on all digits except for their big toes (which have nails), do not have prehensile tails, and don’t have the ability to change their facial expressions.
Our SkyScan 1273 desktop micro-CT allowed us to examine fine details and thin bones in this skull in a scan time of about four hours. We were able to balance resolution with speed due to the wide field of view on the X-ray detector in the SkyScan 1273.
Micro-CT Scan of a Marmoset Skull
Our micro-CT visualization of this marmoset skull allows us to highlight the flexibility and resolution provided in the SkyScan 1273 compared to most other available instruments. As can be seen in Figure 1 above, the marmoset skull is well resolved with great detail in the complex skull bone morphometry.
As can be seen in Figure 2, the teeth are the densest region within the scan. The cortical and trabecular bone comprising the skull is represented with darker values indicating less X-ray attenuation than the teeth.
A powerful feature of micro-CT scans includes the ability to clip or cut away regions of the sample to highlight internal features when viewing the data in a three-dimensional rendering program such as CTVox. One of the greatest strengths of micro-CT examination of samples is the ability to non-destructively image the internal features of samples without affecting subsequent histology or other analysis methods, as we can see in Figure 3. This ability is particularly suited for biological samples, which may often undergo several additional analysis steps after micro-CT.
While micro-CT imaging produces an image stack of data which can be directly analyzed volumetrically utilizing CTAnalysis, often researchers might also be looking for a fixed volumetric file, such as an STL, for either subsequent mechanical or fluid analysis or for reproducing certain features using 3D Printing. Micro-CT data can be quickly converted to these file types and is often used as a preparation step for 3D printing, as shown with the STL model in Figure 4.
Conclusion
Micro-CT is particularly useful in non-destructive examination of bone and biological samples. Even while focusing on small details and thin bones within the sample, the skull imaging process only required about four hours. The wide X-ray camera present on the SkyScan 1273 allows us to balance resolution with speed. We hope you found this Image of the Month informative.
Scan Specifications
Sample | Marmoset Skull |
Voltage (kV) | 110 |
Current (µA) | 136 |
Pixel Size (µm) | 25 |
Rotation Step | 0.25 |
Scan Time (HH:MM:SS) | 04:03:40 |
This scan was completed on our high power desktop SkyScan 1273 system at the Micro Photonics Imaging Laboratory in Allentown, PA. Reconstructions were completed using NRecon and visualization of 2D and 3D results were completed using Dataviewer and CTVox.
This sample was imaged on generous loan from the laboratory of Dr. Elias Issa in the Zuckerman Mind Brain Behavior Institute at Columbia University. For more information on their research programs, please visit their lab site directly.
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