Morphology and immunohistochemistry of the olfactory organ in the bloodfin tetra, Aphyocharax anisitsi (Ostariophysi: Characidae)

LAURA RINCÓN CAMACHO; SANTIAGO PINTOS; ANDREA POZZI; MATIAS PANDOLFI

JOURNAL OF MORPHOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2020 vol. 281 p. 896 - 996

0362-2525

Enormous differences exist in the shape, number, and arrangement of the olfactory lamellae, the distribution of the sensory and non-sensory epithelium, as well as, the abundance of various receptor cells among teleost fishes. The objective of this work was to describe the morphology, immunohistochemistry and scanning electron microscopy ultrastructure of the olfactory epithelium of the bloodfin tetra, Aphyocharax anisitsi. This is the first complete description including the anatomy, histology, and immunohistochemistry of the peripheral olfactory organ from a Characiformes, one of the largest order of Neotropical fishes.Based on the external morphology of the olfactory organ, A. anisitsi was classified as a ditermous species, with an olfactory cavity containing two openings divided by a skin flap, that separates the anterior and posterior nostril. This species belongs to the group of isosmates, since the presence of accessory olfactory sacs was not observed and non-sensory ciliated cells were identified. A. anisitsi presented an olfactory rosette with an arrow-shaped arrangement, with differences in length between the anterior and posterior lamellae. Regarding the structure of the olfactory epithelium, three types of olfactory receptor neurons were identified by histology and its identity confirmed by immunohistochemistry: ciliated olfactory receptor neurons in the basal region of the epithelium; microvillar olfactory receptor neurons in the middle region; and Crypt cells, in smaller numbers compared to the other neuronal types, present in the apical region. Sensory and non-sensory areas were scattered and mixed along the lamellar lateral surface. But the nasal cavity and the midline raphe lacked olfactory receptor neurons. The presence of abundant kinocilia in the non-sensory cells could be related in A. anisitsi with ventilation and quality control of water entering the olfactory cavity. The spatial organization of the sensory and non-sensory areas in A. anisitsi was similar to that observed in other species that also inhabit still and slow-flowing bodies of water with high-density vegetation.