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Guo et al. The distribution of hair in Chinese

Table 3: Percentages of different types of FU (%) Chinese AGA patients.
1-hair FUs 2-hair FUs 3-hair FUs 4-hair FUs 5-hair FUs
Vertex 27.65 53.72 17.23 1.23 0.17 Our research on the distribution of FU types in healthy
Occipital 29.24 51.31 17.96 1.25 0.24 Han Chinese found that 1-hair FUs accounted for
Temporal 28.26 52.84 17.25 1.43 0.22 28.38%, 2-hair FUs accounted for 52.62%, 3-hair
Overall 28.38 52.62 17.48 1.30 0.21 FUs accounted for 17.48%, 4-hair FUs accounted for
1.30%, and 5-hair FUs accounted for 0.21%. No FUs
FU: follicular unit
comprising more than 5 hairs were observed in our
Table 4: Correlation analysis between density of study. The proportions of FU types are different for
[3]
follicular units and age different races . Our research indicates that the FU
types found in healthy Han Chinese are dominated
r P by 2-hair FUs. The result is consistent with the FU
Vertex -0.897 0.000 types of whites, whereas the FU types of Africans are
Occipital -0.876 0.000
Temporal -0.788 0.000 dominated by 3-hair FUs.
r: Spearman correlation coefficient The result of correlation analysis indicated that FU
density decreased with an increase in age; therefore,
As the Chinese population is predominantly Han, it the FU density at the vertex can be used as an
is necessary to investigate and study FU and hair indicator to evaluate the degree of aging in healthy
density in Han Chinese. Han Chinese.

Our study found that the mean FU density in 146 healthy Our research findings have provided some theoretical
Han Chinese was 74.36 ± 13.33 units/cm . This is lower data on the hair distribution characteristics of Han
2
[3]
than the results obtained by Bernstein and Rassman Chinese. These data can contribute to preoperative
2
[8]
and similar to the result by Tsai et al. (71.78 units/cm ). evaluation, surgery planning, and postoperative
There were no statistical differences between males and outcome evaluation performed by hair transplantation
females (P = 0.553). The mean hair density in healthy surgeons. The required amount of hair transplantation,
Han Chinese was 143.33 ± 28.08 hairs/cm , which is area of donor site excision or extraction, postoperative
2
[7]
lower than that in whites and Africans . There were no density, and cost may be estimated, depending on
statistical differences between males and females (P = the area of recipient site during the preoperative
0.464). The mean FU densities of the vertex, occipital, consultation [11,12] . For example in a male patient with
and temporal regions were 83.32 ± 7.75 units/cm ,
2
2
2
82.66 ± 4.12 units/cm , and 57.10 ± 2.97 units/cm , vertex hair loss with a recipient site measuring 2 cm ×
respectively. The mean hair densities were 160.95 ± 2 cm, assuming that all the transplanted FUs survive,
the transplantation of 200 FUs can achieve 60% of
2
2
20.66 units/cm , 158.90 ± 13.41 units/cm , and 110.14 ± the normal density of vertex hair. By mean of FUT, this
2
10.17 units/cm , respectively. These results indicate that 2
there are differences in the FU density and hair density requires a scalp area of about 2.4 cm to be excised
among the different scalp sites of Han Chinese. There from the occipital region. By mean of FUE, according
was no statistical difference between the vertex and the theory that it will be not significantly affect the
occipital regions, but both had significantly higher values occipital region appearance after the extraction of
[3]
than in the temporal region [7-9] . This provides us with 40% the occipital hair follicles , this requires a scalp
2
strong data for the theoretical support of temporal hair area of about 6 cm to be extracted from the occipital
transplantation. region. The transplantation of 300 FUs can achieve
90% of the normal density of vertex hair. This requires
2
The results on the 41 AGA patients indicate that the a scalp area of about 3.6 or 9 cm to be excised or
mean FU density of the occipital region was 77.78 ± extracted from the occipital region.
2.99 units/cm and the mean hair count was 148.12 ±
2
2
6.98 hairs/cm . Both results were lower than those in We hope that our results can serve as a reference
the occipital regions of healthy Han Chinese, and the for clinical practice. In addition, we will continue to
differences were statistically significant (P < 0.001). collect clinical cases to establish a database for hair
Orentreich [10] successfully transplanted non-hormone distribution of Han Chinese for further research.
sensitive hair follicles from the occipital region into
the bald area and proposed the donor dominance DECLARATIONS
theory, which has become the theoretical basis of hair
transplantation surgery for patients with alopecia. Our Authors’ contributions
research data provide a reference to evaluate the Images’ analysis and wrote the article: Z.H. Guo
area of donor site that should be transplanted in Han Collected hair photoes of clinical patients: G. Wang
Plastic and Aesthetic Research ¦ Volume 4 ¦ September 28, 2017 153