The pineal complex: a morphological and immunohistochemical comparison between a tropical (Paracheirodon axelrodi) and a subtropical (Aphyocharax anisitsi) characid species

RINCON CAMACHO L.; MORANDINI, L.; BIRBA, A.; CAVALLINO L.; ALONSO, F.; LO NOSTRO, F.; PANDOLFI, M.

JOURNAL OF MORPHOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2016 vol. 277 p. 1355 - 1397

0362-2525

Cardinal neon Paracheirodon axelrodi andbloodfin tetra Aphyocharax anisitsi are two species ofcharacids with high trade value as ornamental fish inSouth America. Although both species inhabit middlewater layers, cardinal neon exhibits a tropical distributionand bloodfin tetra a subtropical one. In this work, we carriedout an anatomical, histological and immunohistochemicalstudy of the pineal complex of P. axelrodi and A.anisitsi. In both species, the pineal complex consisted ofthree components, the pineal and parapineal organs andthe dorsal sac (DS). The pineal organ was composed of ashort, thin pineal stalk (PS), vertically disposed withrespect to the upper surface of the telencephalon, and apineal vesicle (PV), located at the distal end of the PS andattached to the skull by connective tissue. The pineal window(PW), a site in the skull where the luminal informationaccesses the pineal organ, appeared just above thelatter structures. In the epidermis of P. axelrodi?s PW, clubcells were identified, but were not observed in the epidermisof A. anisitsi?s one. With respect to the DS, itappeared to be folded on itself, and was bigger and morefolded in A. anisitsi than in P. axelrodi. Immunohistochemicalassays revealed the presence of cone opsin-likeand rod opsin-like photoreceptor cells in the PS and PV.These results provide a first insight into the morphologicalassembly of the pineal complex of both species, and contributeto a better understanding of the integration andtransduction of light stimuli in characids