<prompt> Growth Phase of the hair?AnagenMetagenCatagenTelogen  <response>: Ans. A. AnagenHair Growth CycleScalp hair-follicles have a four phase cycle.Anagen growth, Catagen transition, Telogen resting and Exogen hair-shaft evacuation.The Anagen Phase growing phase- During the process of folliculo-regenesis, the follicle epithelial sheath new hair shaft is recreated.- During its growth anagen phase the hair shaft continues to gain length for a period of 2-7 years.- Approximately 80-85 of hair follicles are in anagen.- Hair growth rates range from 0.5cm-1.45cm per month.The Catagen phase involutionary phase- mitosis ceases, the follicle enters a period of degeneration.- Catagen accounts for approximately 3 of hair follicles.- The Epithelial sheath shrinks forming a minute club root at the proximal end of the hair shaft.- Catagen lasts for approximately 10-20 days.The Telogen Phase resting or dying phase- approximately 12-20 of hair shafts are in the amitotic resting phase.- Eventually up to 3 months the hair shaft vacates the follicle.The Exogen Phase- in which the hair-shaft is evacuated. 