Fig. 4. Arachidonic acid (AA) prolongs the anagen hair cycle. (A) The experiment design. Ten days after depilation by waxing, the back skin of C57BL/6 mice was treated with either with the vehicle, topical 3% minoxidil (MNX), or 2% AA. (B) On day 21 after depilation, biopsied skin samples were fixed in paraffin, sectioned and stained with hematoxylin and eosin (×40). (C) Calculating the hair cycle scores. For each mouse (5 mice per group), 50 hair follicles (HFs) from each section were analyzed and graded as follows: anagen VI, 100; early catagen, 200; mid catagen, 300; late catagen, 400. The score indicates the mean hair cycle stage for all HFs in a group. Data are expressed as mean±standard error. CTL: control. ^*p≤0.05, ^***p≤0.001 versus the control group.