Microstructural morphology of dermal and oral denticles of the sharpnose sevengill shark Heptranchias perlo (Elasmobranchii: Hexanchidae), a deep-water species - Rangel, Bianca de Sousa; Amorim, Alberto Ferreira de; Kfoury Junior, José Roberto; Rici, Rose Eli Grassi (Microscopy Research and Technique, 2019)