Ortolani-Machado C F, Freitas P F, Faraco C D
Laboratório de Biologia do Desenvolvimento, Departamento de Biologia Celular, UFPR, Centro Politécnico, Curitiba, Paraná CEP 81531-990, Brazil.
Tissue Cell. 2009 Aug;41(4):239-48. doi: 10.1016/j.tice.2008.11.005. Epub 2009 Jan 10.
The Japanese Silky chicken (SK) shows dermal and visceral hyperpigmentation. This study characterizes ultrastructurally the melanin granules developing in dermal melanocytes of the dorsal skin of SK, in an attempt to better understand the processes of melanogenesis in these permanently ectopic cells. The steps of melanogenesis are similar to those described for epidermal melanocytes, with melanosomes going from stage I to IV but, in SK, the maturation occurs in the cell body, as well as in the cytoplasmic processes. At stage III, the deposition of melanin is cumulative and can aggregate in rounded structures, which combine to turn into the mature granule. The final destiny of mature melanosomes is still unclear, although it was observed that dermal macrophages can accumulate melanin granules in their phagosomes. Even with the close proximity between melanocytes and other dermal cells, the transference of melanosomes was not observed. Our findings indicate that melanogenesis in dermal melanocytes in SK has the same morphological characteristics found in epidermal melanocytes, but the functional aspect still remains to be elucidated.
日本丝羽乌骨鸡（SK）表现出皮肤和内脏色素沉着过度。本研究对SK背部皮肤真皮黑素细胞中发育的黑素颗粒进行了超微结构表征，以更好地了解这些永久性异位细胞中的黑素生成过程。黑素生成步骤与表皮黑素细胞中描述的步骤相似，黑素小体从I期发展到IV期，但在SK中，成熟发生在细胞体以及细胞质突起中。在III期，黑色素的沉积是累积性的，可聚集形成圆形结构，这些结构结合形成成熟颗粒。尽管观察到真皮巨噬细胞可在其吞噬体中积累黑素颗粒，但成熟黑素小体的最终归宿仍不清楚。即使黑素细胞与其他真皮细胞紧密相邻，也未观察到黑素小体的转移。我们的研究结果表明，SK真皮黑素细胞中的黑素生成具有与表皮黑素细胞相同的形态学特征，但功能方面仍有待阐明。
