Structure and function of melanocytes: microscopic morphology and cell biology of mouse melanocytes in the epidermis and hair follicle.
ABSTRACT Melanocytes characterized by their tyrosinase activity, melanosomes and dendrites locate in the basal layer of epidermis and hair bulb in the skin of mice. Melanocytes differentiate from undifferentiated melanoblasts derived from embryonic neural crest. Melanocyte-stimulating hormone plays an important role in the regulation of the differentiation of mouse melanocytes in the epidermis and hair bulb by inducing tyrosinase activity, melanosome formation, transfer of melanosomes and increased dendritogenesis. The proliferative activity of differentiating epidermal melanocytes of newborn mice during the healing of skin wounds is regulated by semidominant genes, suggesting that the genes are involved in regulating the proliferative activity of epidermal melanocytes during differentiation. The morphology and differentiated functions of mouse melanocytes are shown to be influenced by environmental factors such as ultraviolet and ionizing radiations. From the results of serum-free culture of mouse epidermal melanoblasts, basic fibroblast growth factor is shown to stimulate the sustained proliferation of melanoblasts in the presence of dibutyryl adenosine 3',5'-cyclic monophosphate and keratinocytes. In contrast, melanocyte differentiation in serum-free culture is induced by melanocyte-stimulating hormone in the presence of keratinocytes. These results suggest that the structure and function of mouse melanocytes in the epidermis and hair bulb are controlled by both genetic factors and local tissue environment, such as hormones and growth factors.
- SourceAvailable from: Amadi O Ihunwo
- [Show abstract] [Hide abstract]
ABSTRACT: BACKGROUND: Although keratinocyte-derived factors are known to promote the proliferation and differentiation of human epidermal melanocytes, it is not fully understood whether fibroblast-derived factors work in a similar way. OBJECTIVE: The aim of this study is to clarify whether fibroblast-derived factors are involved in regulating the proliferation and differentiation of human melanocytes with or without keratinocytes using serum-free culture system. METHODS: Human epidermal melanoblasts and melanocytes were cultured in a serum-free growth medium supplemented with fibroblast-derived factors such as keratinocyte growth factor (KGF) with or without keratinocytes, and the effects of KGF on the proliferation and differentiation of melanocytes were studied. RESULTS: KGF stimulated the proliferation of melanoblasts in the presence of dibutyryl cAMP (DBcAMP), basic fibroblast growth factor (bFGF), transferrin (Tf), and endothelin-1 (ET-1). Although KGF stimulated the differentiation, melanogenesis, and dendritogenesis in the presence of DBcAMP, Tf, and ET-1 without keratinocytes, KGF required the presence of keratinocytes for the stimulation of melanocyte proliferation. CONCLUSION: These results suggest that fibroblast-derived KGF stimulates the proliferation of human melanoblasts in synergy with cAMP, bFGF, Tf, and ET-1, the differentiation of melanocytes in synergy with cAMP, Tf, and ET-1, and the proliferation of melanocytes in synergy with cAMP, Tf, ET-1, and undefined keratinocyte-derived factors.Journal of dermatological science 04/2013; · 3.71 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Vitiligo is a skin disorder characterized by achromic macules (white) on the skin and/or mucous membranes, which affects 0.5-2% of the population. Few publications address a vitiligo epidemiological profile worldwide. In Brazil there are only studies in children. To assess the clinical and epidemiological profile of individuals affected by vitiligo and to evaluate behavior of the disease in different age groups. We conducted a retrospective cross-sectional study in 669 patients with vitiligo from January 2001 to May 2006, who attended the Faculty of Medicine of ABC, located in the metropolitan region of São Paulo, Brazil. There was a predominance of females (62.2%) and adult age group (62.5%), with higher prevalence peaks between the second and third decades of life (18.3% and 16.9%, respectively). The most frequent phototype in skin was III (49.9%). Lesions began on the face most commonly in children and adolescents (32.6%) and the elderly (23.3%), and on hands in adults (24.0%). There was a higher prevalence of segmental vitiligo in children and adolescents (36.4%), compared with adults (11.3%) and the elderly (6.7%), and vitiligo with stable evolution was proportionately more frequent in childhood and adolescents (46.2%) than in adults (32.5%) and elderly (36.7%). Our findings are similar to other countries, mainly regarding the higher prevalence of segmental vitiligo and vitiligo with stable development among children and adolescents.International journal of dermatology 10/2013; · 1.18 Impact Factor