hair growth. cross section of a human skin with hair follicles

hair growth growing cross follicle anagen phase catagen telogen diagram cycle anatomy skin alopecia human scalp vector medical health bulb papilla loss shaft root dermal care dermis phases medicine scientific anatomical layer crosssection layers removal gland dermatology condition structure problem body cell hairless labeled regressing quiescent factors oil bag stage stem disorder stimulants nutritional hormonal influence genetics prevention transplantation advance research healthy science biology exam knowledge lesson explainer education biochemistry quiz instruction learning training schooling teaching coaching growth follicles follicles