STRUCTURAL DIVERSITY OF OLFACTORY ORGANS IN OSTEOGLOSSIFORMES

  • Sudhanshu Shekhar

Abstract

Osteoglossomorpha, an ancient Teleostei group, exhibits many ancestral structural features. Herein, we describe the diversity in morphology of olfactory organs of air-breathing Pantodon buchholzi, Arapaima gigas, and Gymnarchus niloticus in terms of adaptations to short ventures out of water and compare the results with the water-breathing Osteoglossum bicirrhosum. We demonstrate the presence of olfactory rosettes within the olfactory chamber in all studied species and additionally a peculiar cudgel-shaped structure in P. buchholzi. The typical olfactory rosette with centrally located elongate median raphe and two rows of olfactory lamellae was found only in P. buchholzi. In A. gigas, the olfactory lamellae arranged in semicircular manner were merged to small median raphe. Osteoglossum bicirrhosum and G. niloticus lacked median raphe, while the olfactory lamellae were ordered nearly parallel or circular, respectively. Olfactory epithelium lining the olfactory lamellae was unfolded only in P. buchholzi and G. niloticus. In contrast, in O. bicirrhosum and A. gigas convexities formed by nonsensory cells and concavities made by the sensory component were observed. Among the olfactory sensory neurons, ciliated and microvillus neurons were found in all studied species. Crypt-like cells were noted only in P. buchholzi, whereas rod-like cells were unique for A. gigas. The substantial morphological variation of the olfactory organ structure and ultrastructure in the studied osteoglossiforms may be explained by the early division of Osteoglossomorpha within Teleostei and long-term, independent evolution within the families. Keywords:- Olfactory rosette; olfactory sensory neurons; airbreathing fishes; Teleostei; evolution; olfactory organ structure; Osteoglossiformes.
How to Cite
Sudhanshu Shekhar. (1). STRUCTURAL DIVERSITY OF OLFACTORY ORGANS IN OSTEOGLOSSIFORMES. ACCENT JOURNAL OF ECONOMICS ECOLOGY & ENGINEERING ISSN: 2456-1037 INTERNATIONAL JOURNAL IF:7.98, ELJIF: 6.194(10/2018), Peer Reviewed and Refereed Journal, UGC APPROVED NO. 48767, 6(5), 24-31. Retrieved from https://ajeee.co.in/index.php/ajeee/article/view/2052