The hair forms a sharp angle so that it grows out and then flat to the face. Scalp hair has a much gentler angle. Eyebrow hairs do not grow in the same type of follicular units as scalp hair. Rather than growing in groups of one to four hairs, they are simply single strands of hair. You can see this if you look carefully in the mirror at your eyebrows. A follicular unit is a single entity that is made up of several parts. All these parts are necessary to the whole. The first part, and the one most people getting hair transplant surgery are interested in, is the hairs. There should be one to four full hair follicles in the unit and one or two fine hairs as well. The groundwork is done for them by the surgeon when he does his incisions. The surgical team takes care to get every hair transplant graft into the receptor sites as they have been laid out. They waste no time, though, because the small grafts are vulnerable when their follicles are outside of the skin. Based on the fact that the average Caucasian male has a density of 2 hairs per millimeter, it can be assumed that the average density of hair is 1250 hairs per square inch. Figuring at an average of 2 hairs per follicular unit, it would take 625 follicular units per square inch. To get 25% of that, you would need 156 follicular units per square inch. You need a person with good training to show you all you need to make your mind up about the surgery. You do not need a person whose only agenda is to sell you on getting hair transplant procedures done. 3. You should start to get concerned if your doctor has no specific good stories to tell about hair transplant surgery they have done. How Surgeons Hide Donor Scars during Hair Transplant Surgery Hair transplant procedures leave scars. It is just a fact of life. However, if the surgeries are handled in the proper manner, the scars are barely noticeable. They are thin to the point that they can barely be seen in most cases. Skilled doctors have ways of making the scars practically disappear.