Ultrasonographic imaging of the reproductive organs of the female bottlenose dolphin, Tursiops truncatus aduncas

Abstract

Routine ultrasonographic examination of the reproductive tract was performed for periods of up to 10 years in ten female bottlenose dolphins (Tursiops truncatus aduncas) in Hong Kong. The ovaries could be reliably and repeatedly identified, lying close to the body surface, in the angle formed by the rectus abdominus and hypaxialis lumborum muscles, and were most easily located by scanning in the transverse plane from the proximal end of the genital slit towards the head. The ovaries are ovoid, with a relatively hypoechoic cortex around a central echogenic mesovarium. The echogenicity of the ovarian parenchyma appeared to increase with increasing age. This may be the result of age-related changes, such as increased fat deposition or fibrosis, or of ovarian 'scars' from multiple ovulations. Small antral follicles, developing follicles and corpora lutea can be identified within the ovarian cortex. Owing to its shape and lack of a definitive border, plus the close relationship to the intestines, the contents of which may obstruct the ultrasound beam, the non-pregnant uterus was not so easily visualized. The endometrium was poorly differentiated and difficult to see. To date, examination of the uterus using ultrasonography has provided little information about endometrial changes during the ovarian cycle in this group of dolphins. Real-time diagnostic ultrasonography provides a means to image the morphology of the reproductive organs in live female dolphins directly and provides a valuable means of assessing reproductive events in this species.

Seasonality, estrous cycle characterization, estrus synchronization, semen cryopreservation, and artificial insemination in the Pacific white-sided dolphin (Lagenorhynchus obliquidens)

“…Location and general appearance of ovaries were similar to what has previously been described for bottlenose dolphins and the Indo-Pacific dolphins (Brook 2001, Brook et al 2004. As with these other species, the ovaries were ovoid in appearance with a relatively hyperechoic hilus and hypoechoic cortex (Fig.…”

“…Evaluation of ovaries using transabdominal ultrasonography has been previously reported in other cetacean species including the bottlenose dolphin (Robeck et al 1998, 2005b, Brook 2001, Indo-Pacific humpback dolphin (Brook et al 2004), killer whales , and the beluga ). The circumferential daily growth rate of 0.41 cm and the maximum POF diameter of 1.5 cm in the Pacific white-sided dolphin were different from the bottlenose dolphin of 0.47 and 2.1 cm respectively.…”

“…Transabdominal ultrasonography was used to detail follicular activity during natural cycles, following altrenogest-induced cycles and to confirm pregnancy as previously described for bottlenose dolphins (Brook 2001. Ultrasonographic examinations were performed using either an Aloka 900 machine (SWT: Corimetrics Medical), GE Logibook Book (SWT: GE LogiqGE Medical Systems, Milwaukee, WI, USA), or a SonoSite 180 Plus (Shedd: SonoSite, Inc., Bothell, WA, USA) all with a 3.5 MHz transducer (wide footprint convex linear probe).…”

Prospects for captive breeding of poorly known small cetacean species

“…In addition, long-term, systematic evaluation of endo crine changes (in particular rapid detection of changes in urinary luteinizing hormone) elucidating ovarian activity and collection of these data in conjunction with ultrasound evaluation of ovarian changes and male reproductive characteristics (Brook 2001, Robeck et al 2005b, Robeck and Monfort 2006 were necessary to achieve success with AI in bottlenose dolphins. Likewise, intricate details of reproductive endocrine physiology in female and male killer whales, beluga whales, Pacific white-sided dolphins, and Indo-Pacific bottlenose dolphins were needed to achieve the first successful AI in these species (Walker et al 1988, Robeck et al 1993, 2004, 2005a, O'Brien & Robeck 2010a.…”

B-Mode ultrasonographic evaluation of the testis in relation to serum testosterone concentration in male Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis) during the breeding season

“…In past decades, the clinical application of ultrasonography in veterinary medicine and animal reproduction has expanded dramatically, and the value of this technique in breeding both domestic and nondomestic species has been well documented [14][15][16][17][18][19]. As animals are trained to cooperate, ultrasonographic examinations have aided in determining the reproductive status of captive cetaceans [20][21][22][23]. Nevertheless, no previous research has used this approach to evaluate the reproductive physiology of YFPs.…”