淡水産硬骨魚ドンコの表皮性黒色素胞 : 運動性と微細構造

In the integument of a freshwater goby. Odontobutis obscura, there exist two kinds of melanophores : epidermal and dermal melanophores. The epidermal melanophores are located in the intermediate layer of the epidermis and possess thin perikarya containing round nuclei. and slender. ramified processes that frequently connect with adjacent Processes to form a network. The epidermal melanophores are innervated by the adrenergic nerves. The nervous stimulation induced aggregation of melanosomes in the melanophores through alpha adrenoceptors on their cell membranes. The mechanisms were the same as those of the dermal melanophores. The fine structural features of these cells were very similar to those of the dermal melanopores described previously in various fish species. The epidermal cells loaded with melanin granules were not observed ; the integument of this species could not function as an epidermal melanin unit. Macrophages may be responsible for the catabolism of the pigment since phagocytized melanosomes and melanosome-containing lysosomes were found frequently in neighborhood of the epidermal melanophores.