Baden H P, Kubilus J, Baden L
J Am Acad Dermatol. 1979 Aug;1(2):121-2. doi: 10.1016/s0190-9622(79)70008-9.
Anagen and telogen plucked hairs may be difficult to distinguish based on their microscopic appearance. The root ends of plucked anagen hairs develop a red color when stained with 4-dimethylaminocinnamaldehyde, while those of plucked telogen hairs do not. This is the result of a reaction with citrulline-containing proteins in the internal root sheath. This histochemical stain provides a simple and accurate means of determining the telogen/anagen ratio in plucked hairs.
