鳜皮肤图案中色素细胞的分布与排列

色素细胞是皮肤图案形成的基础,为了解鳜(Siniperca chuatsi)皮肤图案区域色素细胞的种类、分布及排列特征,采用光学显微镜与电子显微镜对鳜皮肤中图案区域、非图案区域及交界处皮肤的色素细胞进行显微及超显微结构观察。结果显示,鳜皮肤中含有黑色素细胞、黄色素细胞、红色素细胞及虹彩细胞,主要分布于表皮层和色素层。头部过眼条纹、躯干纵带、躯干斑块等图案区域皮肤表皮层与色素层均含有黑色素细胞,非图案区域仅表皮层含有少量黑色素细胞。躯干图案区域(纵带、斑块)皮肤色素层色素细胞分布层次明显,由外到内依次为黄色素细胞、红色素细胞、黑色素细胞和虹彩细胞,其中,虹彩细胞内反射小板较长,整齐水平排列;躯干非图案区域皮肤色素层由外到内依次为黄色素细胞、红色素细胞和虹彩细胞,其中,虹彩细胞内反射小板较短,无规则排列。头部过眼条纹色素层含有4种色素细胞,色素细胞数量较少,且无规则排列,其中,黑色素细胞内黑色素颗粒较大。交界处皮肤色素层黑色素细胞数量向非图案区域一侧逐渐减少,虹彩细胞数量逐渐增加。结果表明,鳜图案区域与非图案区域、不同图案区域的色素细胞分布与排列各不相同,本研究结果为鳜色素细胞图案化形成机制提供了基础资料。

Distribution Patterning of Pigment Cells in the Skin of Mandarin Fish Siniperca chuatsi

Pigment cells are the basis of skin pattern formation. In order to understand different types and arrangement of pigment cells in different skin pattern areas of mandarin fish (Siniperca chuatsi), the skin from pattern area, non-pattern area and their junction area were observed with light and electron microscopes. The results showed that the skin contained melanophores, xanthophores, erythrophores and iridophores, which were mainly distributed in the epidermis and pigment layer. The pattern areas include eye stripe, trunk band and trunk spots that contained melanophores in both the epidermis and pigment layer. The skin non-pattern area only contained a small amount of melanophores in the dermis (Fig. 2). In the skin trunk pattern area (band, strips), different pigment cells were obviously distributed in order in pigment layer: from the outside to the inside, xanthophores, erythrophores, melanophores and iridophores were distributed (Fig. 5b), and the reflective platelets in iridophores were long and neatly arranged horizontally (Fig. 5e). In the non-patterned areas of the trunk xanthophores, erythrophores and iridophores were observed from the outside to the inside (Fig. 5c), and the reflective small plates in iridophores were short and irregularly arranged (Fig. 5f). Pigment layer of the eye stripe contained these four kinds of pigment cells, and the number of pigment cells which were irregularly arranged in this region was small, and melanin granules were large in size (Fig. 5a). At the skin junction area, the number of melanophores in the pigment layer gradually decreased toward the non-patterned area, while the number of iridophores gradually increased (Fig. 5d). The result showed that the types, distributions and arrangements of pigment cells were distinctly different among pattern areas, non-pattern area and junction area. Results of this study provide some basic information for understanding pigmentation patterning mechanism in mandarin fish.