The hair follicles are not evenly distributed on the scalp but they are arranged naturally in minute groups, called "follicular units". These units house 1, 2 or 3 (seldomly 4) hair follicles, standing very close together. On 1 square centimetre are approx. 60- 110 follicular units. The knowledge about the follicular units was of great importance in developing further hair transplant technique. At first the knowledge about the follicular units enabled aesthetic hair transplant surgery (see actual used techniques ). In modern hair transplant surgery a follicular unit is equivalent to a graft. A graft is one single transplant in hair transplant surgery.

  Fig. 5 a: short cut scalp hairs with well detectable follicular units

Fig. 5 b: Photomicrograph of two adjacent follicular units. The left unit has 2, the right unit has 3 hair follicles.