Ultrastructural and immunohistochemical characteristics of the olfactory organ Cardinal tetra, Paracheirodon axelrodi (Characiformes: Characidae)

RINCÓN-CAMACHO, L; JUNGBLUT, L D; PANDOLFI, M; POZZI, A G

JOURNAL OF MORPHOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2022

0362-2525

The cardinal tetra Paracheirodon axelrodi (Schultz, 1956) belongs to the family Characidae, an important and diverse family of fishes, but about which information on the olfactory system remains scattered and scarce. Among teleost fishes, differences exist in the shape, number, and arrangement of the olfactory lamellae, in the distribution of the sensory and non-sensory epithelium, as well as in the abundance of various receptor cell types. Here, an anatomical and morphological description of the olfactory system was carried out through classical histology, immunohistochemistry, scanning electron microscopy, and transmission electron microscopy. P. axelrodi is a ditremous and isosmat species. It has an arrow-shaped olfactory rosette arrangement. The olfactory epithelium is found covering the 12 to 14 lamellae of the olfactory rosette and, by SEM, it was observed that the apical surface of the olfactory epithelium presents a dense layer of mucus. Based on the histological, immunohistochemical, and ultrastructural descriptions, all the characteristic sensory and non-sensory cell types of the olfactory epithelium of teleost fish were identified. Three types of olfactory receptor neurons were identified: ciliated, microvilli, and crypt cells. The distribution of sensory and non-sensory cell types is like that described in Aphyocharax anisitsi, another species of the Characidae family. A. anisitsi inhabits slow-flowing water bodies with high-density vegetation such as P. axelrodi. Given that many aspects of the basic biology of P. axelrodi is still unknown and there is only partial information on the olfactory system of the Characidae family, this would be the first description made of this species.