A Morphological and ¹³C NMR Study of the Extramandibular Fat Bodies of the Striped Dolphin (Stenella coeruleoalba)

Abstract

The molecular and histological structure of the fat bodies covering externally the posterolateral region of the jaw of the striped dolphin (Stenella coeruleoalba) was investigated by means of morphological and nuclear magnetic resonance techniques. The analyses of samples belonging to adult and juvenile individuals were performed with the aim of seeking the presence of age-related differences. In our study, the level of isovalerate (iso5:0) in the extramandibular fat of the juvenile individuals is comparable with those of the adult counterparts; conversely, longer isobranched fatty acids were detected in lower quantities in the juveniles together with a higher degree of unsaturation. The morphologic analyses revealed that, in both adults and juveniles, this fatty tissue is similar to univacuolar adipose tissue. However, in the juveniles, a muscular component was present, whereas only in adult subjects, enlarged and irregularly shaped cavities may be seen within the adipose tissue. These cavities, structurally organized as veins, may regulate blood flow in response to changing water temperature and stabilize thermal gradient within the jaw lipids. These data suggest that the molecular components and the histological organization can indicate a maturation of the organ with age that probably may reflect different sound reception properties. Anat Rec, 290:913-919, 2007. 2007 Wiley-Liss, Inc.Key words: extramandibular fat; striped dolphin; NMR; morphology; lipids Several marine mammals have evolved an echolocating system called biosonar. In particular, odontocetes echolocate by producing clicking sounds and receiving and interpreting the resulting echo. By means of this system, toothed whales and dolphins can identify objects and animals out of their sighting range, thus obtaining information on their size, number, shape, texture, and speed (Kuc, 1996;Hoffmann et al., 1998;Au, 2002).The organs devoted to the production and propagation of the sound are the ''monkey lips''/dorsal bursa (MLDB complex) and the melon, respectively. The echoed sounds are received and conducted through the lower jaw to the middle ear, inner ear, and then to hearing centers in the brain by means of the auditory nerve. The brain receives the sound waves in the form of nerve impulses, which relay the messages of sound and enable the dolphin to Abbreviations used: iso5:0 ¼ isovaleric acid; NMR ¼ Nuclear Magnetic Resonance; TAG ¼ triacylglycerols; WE ¼ wax esters; mol% ¼ molar; MUFA ¼ mono unsaturated fatty acids; PUFA ¼ poly unsaturated fatty acids; 2-MBA ¼ 2-Methylbutyric acid; IBA ¼ Isobutyric acid.

Vascularization of Air Sinuses and Fat Bodies in the Head of the Bottlenose Dolphin (Tursiops truncatus): Morphological Implications on Physiology

“…We have observed extensive vascularization in three of the largest acoustic fat bodies of dolphins, namely the melon, intra-mandibular fat body (IMFB), and extra-mandibular fat body (EMFB) (Figures 1 and 6–8) in agreement with the observations of Fraser and Purves (1960), Maxia et al (2007), and Slijper (1936) (for more complete descriptions of the fat bodies see Norris, 1969; Norris and Harvey, 1974; Cranford et al, 1996, 2008a; Koopman et al, 2003; Scano et al, 2005; Harper et al, 2008; McKenna et al, 2011). The melon fat is located on the dorsorostral aspect of the skull, extending from the rostral border of the nasal passage to the apex of the melon.…”

The extracranial venous system in the heads of beaked whales, with implications on diving physiology and pathogenesis

“…Much of the EMFB is invested with a sizable but fairly diffuse venous plexus (Figs. and ), similar to those described in the bottlenose and striped dolphins (Maxia et al, ; Costidis and Rommel, ). As with the arterial supply to the EMFB, considerable venous drainage occurs through the mandibular labial vein on the dorsolateral aspect of the mandible (Fig.…”

Nitrogen solubility in odontocete blubber and mandibular fats in relation to lipid composition

“…Again, work on the topology of odontocete fats has demonstrated that these tissues are highly heterogeneous (Wedmid et al, 1973;Karol et al, 1978;Koopman et al, 2006;Maxia et al, 2007;Zahorodny Duggan et al, 2009). Consistency of sampling locations was the goal in this study, but mandibular fats were not sampled on a fine spatial scale for lipid composition analyses, because the N 2 experiments required relatively large amounts of lipid.…”