Dermal and epidermal chromatophores of the Antarctic teleost Trematomus bernacchii.
The physiological response and ultrastructure of the pigment cells of Trematomus bernacchii, an Antarctic teleost that lives under the sea ice north of the Ross Ice Shelf, were studied. In the integument, two types of epidermal chromatophores, melanophores and xanthophores, were found; in the dermis, typically three types of chromatophores--melanophores, xanthophores, and iridophores--were observed. The occurrence of epidermal xanthophore is reported for the first time in fish. Dermal melanophores and xanthophores have well-developed arrays of cytoplasmic microtubules. They responded rapidly to epinephrine and teleost melanin-concentrating hormone (MCH) with pigment aggregation and to theophylline with pigment dispersion. Total darkness elicited pigment aggregation in the majority of dermal xanthophores of isolated scales, whereas melanophores remained dispersed under both light and dark conditions. Pigment organelles of epidermal and dermal xanthophores that translocate during the pigmentary responses are carotenoid droplets of relatively large size. Dermal iridophores containing large reflecting platelets appeared to be immobile.
Obika
M
M
Department of Biology, Keio University, Yokohama, Japan.
Meyer-Rochow
V B
VB
D000818:Animals; D002856:Chromatophores / Q000502:physiology / Q000648:ultrastructure*; D004817:Epidermis / Q000648:ultrastructure*; D005399:Fishes / Q000033:anatomy & histology*; D008547:Melanophores / Q000648:ultrastructure; D012867:Skin / Q000648:ultrastructure*