Here is some information on the following thread.
http://www.hairlossexperiences.com/view_topic.php?id=1083&forum_id=2&page=2
Hair naturally exits the scalp at an angle. It is important to follow this angle for a number of reasons. First, the natural angle will create a more natural flow and look. Second, following the natural angle when making incisions will limit transaction and damage to neighboring residual native hair. Preserving this hair adds to density. Finally, proper angling will create a shingling effect that increases the effectiveness of hair at producing density. The shingling effect that occurs when hair is placed at a more acute angle positions the hair so the surface area lies between the scalp and the eye. It also causes the hair to overlap creating a greater illusion of density. In the past, physicians made the mistake of placing hair in a more perpendicular angle to the scalp. We know that the hair should exit at an angle between 15 and 45 degrees, depending on the location. In the central area, the angle is typically between 30 and 45 degrees. In the hairline, the angle is usually between 15 and 25 degrees. In the temporal points, or eyebrow area, the hair is placed at very acute angle of 0 to 10 degrees. Coronal incisions are useful tools where the hair has to be placed at a more acute angle.
Shapiro Medical article.
