Scanning electron microscopy of the peripheral olfactory organ in small and large juvenile Apogon cyanosoma (Apogonidae:Teleostei)

The olfactory organ in small and large juveniles of the tropical yellowstriped reef cardinalfish Apogon cyanosoma, collected from the wild (total length [TL] range=17-32 mm, mean=25 mm) was examined fly scanning electron microscopy The olfactory organ consisted of two bilaterally radial rosettes in each fish. They were oval-shaped, located medioventrally, one in each of the olfactory chambers. In small juvenile A. cyanosoma the rosette comprised six lamellae, three oil each side of a midline raphe while large juveniles had eight. lamellae, four on each side. The lamellae had a continuous cover of cilia, except for the margins. In small juvenile A. cyanosoma (TL mean=24.3 mm) only microvilli were observed, whereas both microvilli and a, few cilia, presumably From olfactory receptor neurons, Were observed in large juvenile A. cyanosoma (TL mean=32 mm).