A Affordable Hair Transplants San Francisco surgeon removes a strip of healthy hair from the back of the head. The hair in this region is resistant to DHT (dihydrotestosterone), a chemical that is responsible for hair loss. This is why we often see men with only a “wreath” of hair at the back and sides of the head. Once the surgeon has removed the strip of hair from the donor site, the follicular units of one to four hairs are divided into individual grafts which are transplanted to areas of hair loss at the top and front of the scalp.