Medullary index

In some fibers, very few medullary cells are present and the medullary canal appears as a well-defined air-filled space. Bnmner and Comans have classified the medulla on the basis of its absence or interruption [161]. Alternatively, in the forensic sciences, Clement et al. have classified human medullae as either intermediate or fragmental [162]. The latter used the ratio of medulla diameter to hair diameter to obtain the medullary index (MD/HD = MI). 

At the crime scene, various fibers and hairs are collected by policemen. They are immediately examined at the forensic laboratory in order to identify the suspect and help solve the crime. The examination needs to establish (1) whether it is a hair or a fiber (synthetic or plant) (2) its species if it is a hair (3) its somatic origin if it is a human hair (4) whether it is similar to the suspect or the concerned persons. Microscopic examination will resolve the first point. It will also allow discrimination between human and animal hair, as the medulla of human hair does not develop well and shows less than 0.30 of medullary index (ratio of medulla diameter to hair diameter). But determining the species of animal requires experience in animal hair examination. Almost every animal hair shows specific shape of cuticule and medulla under microscopical observation. With regard to the somatic origin of human hair, there are some basic features that usually indicate the bodily origin of the hair. For example, head hair has long length, 30-120 pm diameter, tapered tip, little diameter variation, various medullation, sometimes cut tips, and treatment. Pubic hair has a twisted... 

Other changes such as disturbance of flow pattern, increase of resistive index or variations of cortico-medullary differentiation are influenced by renal function, cardiac situation and medication. Only rarely US-guided renal biopsy is performed. Additional imaging is not necessary except for extra-renal queries related to chronic renal failure and ESRD and for ore-transplantation workup. 

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