Morphology

To evaluate hair follicle morphology, we use histochemical detection of endogenous alka­line phosphatase activity. Alkaline phosphatase is an excellent marker of dermal papilla cells, and is known to be expressed in dermal papilla throughout the hair cycle. This allows visualization of dermal papilla morphology as a useful morphological marker for studying the hair follicle cycle [29, 79]. The criteria for recognizing the key stages of hair follicle growth and development of the regression (catagen) stage has been reported in literature [28, 29], and it may help to understand and evaluate hair follicle response to laser treatment.