What is the difference between the medulla of human and animal hairs?

The medulla of human hairs is typically absent or very thin, often appearing as a fragmented pattern, while in many animal hairs, it is more prominent and can be continuous or well-defined. The structure and pattern of the medulla can vary significantly among different animal species, often aiding in species identification. This difference in medullary structure is one of the key factors used in forensic analysis to differentiate between human and animal hair samples.