Characteristics of the progression of squamation and the formation of ctenii in the Japanese flounder, Paralichthys olivaceus

Abstract

AbstractThe progression of squamation and the formation of ctenii in developing juveniles of completely ambicolorate specimens of the Japanese flounder, Paralichthys olivaceus (Temmink et Schlegel), have been examined and compared with those of normally colored fish. The squamation developed with a similar pattern on both the ocular and blind sides of completely ambicolorate fish and of normal fish. In the normal fish, formation of ctenii occurred only on the ocular side and not on the blind side. In the completely ambicolorate fish, the formation of ctenii occurred on both the ocular and the blind side, but the formation of ctenii on the blind side differed from that on the ocular side in both normal and completely ambicolorate fish in terms of both mode and pattern. On the blind side of ambicolorate fish, the formation of ctenii progressed not from the lateral axis as is the case in the normal fish, but from the dorsal and ventral edges just after the formation of ctenii reached the edges on the ocular side, suggesting the diffusion of an unknown factor(s) through the dermal tissue.