Wherever you take the hair from is called the donor site. There can be different donor sites for different people. The most common donor site for hair transplant surgery is on the head. If the sides and back of your head have full lustrous hair, you are in luck. This hair can be used as donor hair to replace hair you have lost on your balding spots. 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. 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. There are sebaceous glands in the follicular unit which produce oil. The follicular unit is a living unit with muscle, nerves and blood vessels that are all tiny enough to fit into this small package. Then, you will be given instructions to make your hair transplant surgery go better. Some of the items on the list might seem like the doctor is interfering with your life, but they are truly necessary if you are to get the best outcome. You will be told to quit smoking, at least until after you have healed from the surgery, if you are a smoker before the hair transplant procedure. They looked quite unnatural; if a person had hair plugs, everyone knew it. They were not only unbecoming, they were also permanent. Improvements were made in hair transplant surgery in the 1980s. Mini-grafts were better, but they still had the appearance of plugs, albeit smaller plugs. These were made up of 5-8 hairs each. Your skull may feel very unusual for weeks. However, the pain of hair transplant cannot actually be compared to a tooth extraction. Hair transplant pain is decidedly less sharp and some do not even feel it as pain at all. Many people simply feel it as an uncomfortable feeling. If they do feel any pain, it is of a degree that can be taken care of with a few doses of Tylenol.