Collagen Fibers in Crocodile Skin and Teeth: A Morphological Comparison Using Light and Scanning Electron Microscopy

Collagen is one of the most versatile tissues of living organisms that comes in many shapes and sizes, providing functions ranging from tissue matrix through, ligament formation up to enabling mineralization in teeth. The detailed light microscopy and Scanning Electron Microscopy (SEM) observations conducted in this study, allowed us to investigate morphology, sizes and crimp patterns of collagen fibers observed in crocodile skin and teeth. Moreover, the microscopy study revealed that although two completely different tissues were investigated, many similarities in their structure based on collagen fibers were observed. Collagen type I is present in crocodile skin and teeth, showing the flexibility in naturally constructed tissues to obtain various functions. The crimp size investigation of collagen fibers confirmed experimentally the theoretical 67 nm D-periodicity expected for collagen type I. The collagen in teeth provides a matrix for crystal growth and in the skin provides flexibility and is a precursor for corneous scales. Importantly, these observations of the collagen in the skin and tooth structure in crocodiles play an important role in designing biomimetic materials with similar functions and properties.