title: Gross anatomy and histology of the olfactory rosette of the shark Heptranchias perlo.
abstract: Sharks belonging to the family Hexanchidae have six or seven gill slits, unlike all other elasmobranchs, which have five gill slits. Their olfactory organs have a round shape, which is common for holocephalans, but not for elasmobranchs. Thus, the shape of the olfactory organ represents a further, less striking, peculiarity of this family among elasmobranchs. Despite that, the microscopic anatomy and histology of the olfactory organ have not yet been studied in any species of this family. Here, an anatomical and histological description of the olfactory organ of the sharpnose sevengill shark Heptranchias perlo is given. The organ is a rosette, with a central raphe and 31-34 primary lamellae, which bear secondary lamellae with a more or less branched shape. The elastic connective capsule which envelops the olfactory rosette possibly changes its shape along with water influx. In the olfactory epithelium, the supporting cells also have a secretory function, while no specialized mucous cells are visible; regarding this feature the olfactory epithelium of H. perlo differs from that of other chondrichthyan species. The immunohistochemical investigation of the sensory epithelium shows the absence of immunoreactivity for Gαolf in receptor neurons, which confirms previous observations in Chondrichthyes.
authors.affiliation: DISTAV - University of Genoa, Viale Benedetto XV 5, 16132 Genoa, Italy. Electronic address: sara131274@gmail.com.
authors.forename: Sara
authors.initials: S
authors.lastname: Ferrando
authors.affiliation: DISTAV - University of Genoa, Viale Benedetto XV 5, 16132 Genoa, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Gallus
authors.affiliation: DISC - University of Genoa, Largo Rosanna Benzi 8, 16132 Genoa, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Amaroli
authors.affiliation: ISMAR - CNR, via de Marini 6, 16149 Genoa, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Gambardella
authors.affiliation: Department of Fresh Water Biology and Fisheries, Faculty of Natural Sciences, University of Sindh, Jamshoro, Pakistan.
authors.forename: Baradi
authors.initials: B
authors.lastname: Waryani
authors.affiliation: ISMAR - CNR, via de Marini 6, 16149 Genoa, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Di Blasi
authors.affiliation: ISMAR - CNR, via de Marini 6, 16149 Genoa, Italy.
authors.forename: Marino
authors.initials: M
authors.lastname: Vacchi
mesh_terms: D000818:Animals; D003238:Connective Tissue / Q000033:anatomy & histology; D004848:Epithelium / Q000033:anatomy & histology; D009666:Nose / Q000033:anatomy & histology*; D012754:Sharks / Q000033:anatomy & histology*
keywords: Chondrichthyes; Hexanchidae; Olfaction; Sharpnose sevengill shark