Not true about hair cycle:: (A) Telogen phase last for 3 months, (B) 40% of hair is in anagen at one point of time, (C) Catagen is an involutionary period, (D) Telogen is the period between catagen and the next anagen
Answer is B. Ans. b. 40% of hair is in anagen at one point of time.80-90% of hair follicles at a given time are in the anagen phase.Hair follicles undergo a repetitive sequence of growth and the rest, it is known as the hair cycle. Three phases of Hair Cycle are: Anagen, Catagen, and Telogen.Anagen:#Period of active hair growth (determine the final length of the hair).#The entry of a resting hair follicle into anagen is heralded by the onset of mitotic activity in epithelial cells overlying the dermal papilla at the base of the follicle (the secondary epithelial germ).#Under normal circumstances, 80-90% of hair follicles on the human scalp are in anagen at any one time.#It can be identified by the presence of angulated root.Catagen:#At the end of anagen, epithelial cell division declines and ceases, and the follicle enters an involutionary phase known as catagen.#During catagen, the proximal end of the hair shaft keratinizes to form a club-shaped structure and the lower part of the follicle involutes by apoptosis. Clubbing is first seen in catagen and becomes more prominent in telogen phase.#The basement membrane surrounding the follicle becomes thickened and corrugated to form the 'glassy membrane'.Telogen:#It is the time period between catagen and the next anagen.#It lasts for about 3 months.#Club hair is eventually shed through an active process called exogen.#In the human scalp, hair follicles may remain in a state of latency, also known as kenogen, for a prolonged period after the club hair is shed.