A new morphometric technique for assessment of melanization in skin of guinea pigs.
BACKGROUND
The degree of melanization is an important finding in many skin disorders. An objective measurement of melanin density is needed to achieve an accurate evaluation.


OBJECTIVE
The present work aims at translating the subjective increase of melanin particles after narrow band ultraviolet-B (NB-UVB) irradiation into objective numerical values ready for statistical analysis.


METHODS
This study had involved 18 guinea pigs that were exposed to biweekly sessions of NB-UVB radiation for 4 weeks to induce skin pigmentation. Two skin biopsies were obtained from each animal; the first before treatment and the second at the end of the study, using 5 mm punch and stained with hematoxylin and eosin and Masson-Fontana (MF) stains. Surface area of both the epidermis (ESA) and the melanin particles (MPSA) were measured in μm(2) using a software supplied with Olympus light microscope. The MPSA/ESA percentage was calculated for each biopsy. The results before and after NB-UVB exposure were compared and statistically analyzed.


RESULTS
In the MF-stained sections, the mean ± SD of the MPSA/ESA percentage were 0.24 μm(2) ± 0.09 and 6.21 μm(2) ± 2.45 at the start of the study and at its end, respectively, with a highly significant difference (P < 0.001).


CONCLUSIONS
This technique offers a new methodology for an accurate numerical evaluation of epidermal melanization.
Dermatology Department, Al- Minya University, Al- Minya, Egypt. taganbar@yahoo.com
Tag S
TS
Anbar
Tarek S
TS
El-Ammawi
Manal T
MT
Barakat
Amal T
AT
Abdel-Rahman
Ahmed
A
Fawzy
D000818:Animals; D004817:Epidermis / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006168:Guinea Pigs; D008543:Melanins / Q000378:metabolism*; D012871:Skin Diseases / Q000378:metabolism* / Q000473:pathology*; D012880:Skin Pigmentation / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*
D008543:Melanins