Scientific Literacy Essay – Burmese Python Intestinal Crypt Cells
Background
Intestinal plasticity is an adaptation in animals that allows them to shut down their intestine in order to conserve energy. Only certain animals have this adaptation, and the adaptation is usually seen in animals that go long periods without eating, such as most snakes. Unlike mammals or birds that feed daily due to their fast metabolisms, snakes often fast for long periods of time. When they do eat, they often have to digest a food source that can be larger than half of their own body weight. To make their metabolism more efficient, snakes have developed intestinal plasticity which allows snakes to essentially turn off their intestine. For example, during fasting, the tissues in the intestine will shrink and the enzymes will also decrease, resulting in overall energy usage (Andrew, 2015). After feeding, the opposite occurs and there is a dramatic transformation. New cells are formed, digestive enzymes rise, and nutrient absorption increase. This rapid remodeling is what biologists call intestinal plasticity, and it allows snakes to be extremely efficient at maximizing their energy by only using it when necessary. This adaptation is often seen in sit-and-wait predators, such as the Burmese Python.
Plasticity is a common theme in life, and is not limited to digestion. In vertebrates, maintaining proper levels of calcium and phosphorus in the body is equally important and requires precise hormonal control. Calcium, for instance, is essential for bone strength, but it is also critical for nerve impulses and muscle contractions. The parathyroid glands secrete parathyroid hormone (PTH) when calcium/phosphorous levels drop. PTH acts on bones, kidneys, and the intestine (through vitamin D activation) to bring calcium back into balance (Bringhurst et al., 2018). Inversely, calcitonin is a hormone produced by the thyroid gland that reduces blood calcium levels. When calcium levels rise too high, calcitonin helps by preventing bones from releasing calcium and encouraging calcium storage in bone tissue. In short, PTH increases blood calcium levels while calcitonin decreases blood calcium levels, and together they maintain homeostasis (Carter, 2006).
For both intestinal plasticity and the homeostasis of elements such as calcium and phosphorous, biologists rely on advanced tools to visualize the microscopic cells involved. Electron microscopy is one tool, which works by shooting beams of electrons at a specimen, which allows biologists to achieve magnifications far beyond traditional microscopes (because electrons are smaller than wave of light used in light microscopes). Transmission electron microscopy (TEM) reveals the inner structure of cells, allowing biologists to see a detailed shape of the specimen. Another type is scanning electron microscopy (SEM), which provides sharp, three-dimensional image of the surface of a specimen. These methods have been invaluable to biology on their own, but in combination with new technologies, we have been able to learn even more about our world. For example, electron microscopy can be combined with Energy-Dispersive X-ray (EDX) analysis. EDX identifies which elements are present in a specimen by detecting unique X-rays that are emitted when electrons strike atoms (Scimeca, 2018). This means researchers can not only see tissue structures but also determine their chemical makeup. For example, EDX can map where calcium is located in bone or detect nutrient distribution in intestinal tissue. Many new discoveries are being made with EDX, such as in urinary analyses to identify the cause of different urinary tract infections (Yacouba, 2023). Such methods allow biologists to relate structure and chemistry, offering insights and solutions that would be impossible otherwise.
Data Analysis
The intestinal crypts of Burmese Python that are fed mice with their skeletons intact and a calcium-rich diet have a very similar appearance. The cells appear larger and microvilli are elongated and all crypts contain particles. These particles appear as concentric circles and contain mostly calcium and phosphorus, along with oxygen, iron, and sulfur, which was found via energy-dispersive X-ray (EDX) (Lignot et al., 2025).
On the other hand, snakes that are fasting contain apical crypts that are empty of particles. The epithelial cells of the intestine are shrunk and microvilli are shortened. Interestingly, in the pythons that were fed boneless mice, we see the epithelial cells and microvilli grow like normal, and there are particles in the apical crypt. However, through EDX analysis, we know that the contents of the apical crypts contains the same particles (phosphorus, oxygen, iron, and sulfur), but lacks calcium (Lignot et al., 2025). In addition, electron microscopy shows that instead of appearing as concentric circles, the particles visually appear as electron-dense granules.
Regulation of blood calcium in Burmese pythons involves the typical vertebrate hormones parathyroid hormone (PTH) and calcitonin. In fasting and normally fed snakes, blood calcium, calcitonin, and PTH levels remain stable. However, with a low-calcium (boneless) diet, calcium levels are low and we see PTH levels rise sharply, indicating an attempt to restore calcium balance by breaking down the calcium in bones. Calcitonin levels remain relatively constant, even under varying calcium conditions. When calcium is abundant in the diet, the snakes excrete the excess via these crypt particles, maintaining stable blood calcium levels (Lignot et al., 2025).
I think that the authors make a good case that these could be a new type of cell. They are definitely differentiated from the other types of cells we see in the intestine of burmese pythons, at least from the images they included. I would want this study to have a higher sample size; 3-5 snakes is very low and I believe it was conducted on only juveniles. Both sexes of snakes should be used and even other snake species.
References
Andrew, A. L., Card, D. C., Ruggiero, R. P., Schield, D. R., Adams, R. H., Pollock, D. D., Secor, S. M., & Castoe, T. A. (2015). Rapid changes in gene expression direct rapid shifts in intestinal form and function in the Burmese python after feeding. Physiological Genomics, 47(5), 147–157. https://doi.org/10.1152/physiolgenomics.00131.2014
Carter, P. H., & Schipani, E. (2006). The roles of parathyroid hormone and calcitonin in bone remodeling: Prospects for novel therapeutics. Endocrine, Metabolic & Immune Disorders – Drug Targets, 6(1), 59–76. https://doi.org/10.2174/187153006776056666
Lignot, J.-H., Pope, R. K., & Secor, S. M. (2025). Diet-dependent production of calcium- and phosphorus-rich “spheroids” along the intestine of Burmese pythons: Identification of a new cell type? Journal of Experimental Biology, 228(14), jeb249620. https://doi.org/10.1242/jeb.249620
Scimeca, M., Bischetti, S., Lamsira, H. K., Bonfiglio, R., & Bonanno, E. (2018). Energy Dispersive X-ray (EDX) microanalysis: A powerful tool in biomedical research and diagnosis. European Journal of Histochemistry, 62(1), Article 2841. https://doi.org/10.4081/ejh.2018.2841
Yacouba, A., et al. (2023). Use of scanning electron microscopy and energy dispersive X-ray microanalysis in biological samples. Journal of Electron Microscopy and Technology. https://doi.org/10.1002/jemt.24301