Meeting Abstract
25.10 Jan. 5 The Gross Morphology and Fiber Architecture of the Melon in Bottlenose Dolphins, Tursiops truncatus HARPER, C/J*; MCLELLAN, W/A; ROMMEL, S/A; DILLAMAN, R/M; GAY, D/M; PABST, D/A; UNC Wilmington; UNC Wilmington; UNC Wilmington; UNC Wilmington; UNC Wilmington; UNC Wilmington cjh8891@uncw.edu
The melon is a uniquely derived lipid structure located in the odontocete forehead that functions to propagate echolocation sounds into the surrounding aquatic environment. To date, the melon�s abilities to guide and impedance match biosonar sounds to seawater has been attributed to its unique fatty acid composition. The melon, though, is also a connective tissue structure that is acted upon by two groups of facial muscles � the rostral and nasal plug muscles. The goals of this study were to investigate the gross morphology of the melon and to describe the connective tissue fiber populations within the melon. The melon�s gross morphology was investigated by serially sectioning the dolphin forehead in three orthogonal body planes to identify the soft tissue connections between the melon and the surrounding muscles and blubber. The melon was also thin-sectioned in three body planes and polarized light was used to reveal the birefringent collagen fibers within the melon. The melon is reinforced by highly organized populations of connective tissue fibers, most of which appear to be tendons of facial muscles. Along the ventral floor of the melon, there is a horizontally oriented fiber population tethered between the right and left facial muscles. These fibers appear to mechanically separate the nasal plug from the melon and may have a retinacular function. The tendons of the rostral muscles traverse through the body of the melon and either join tendons from the contra-lateral muscles, or insert into the outer blubber. This morphology suggests that the facial and rostral muscles may produce shape change and/or pressure change within the melon, which may affect how sound propagates through the melon.
