15. Functional Morphology of the Reproductive System in Cetacea

Slijper, E.J.

doi:10.1525/9780520321373-017

Cited by 38 publications

(17 citation statements)

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“…Regarding the sperm analysis (by light microscopy), we observed that Stenella clymene sperm exhibit the same characteristics observed previously in other cetaceans (Slijper, 1979, 1996). The use of scanning electron microscopy allowed us to evaluate the precise morphology of the spermatozoa of Stenella clymene, which was helpful for observing the elongated head with a square shape, similar to that described in other cetaceans such as Sousa plumbea , Stenella attenuata and Steno bredanensis (Meisner, Klaus, & O’Leary, 2005) but different from that observed in species such as Tursiops truncatus (Fleming et al, 1981) and Kogia simus (Meisner et al., 2005), whose sperm also present an elongated head but without a square shape.…”

Section: Discussionsupporting

confidence: 86%

“…The location, function and structure of the penis are similar to those observed in other cetaceans, especially other odontocetes (De Guise, Bisaillon, Séguin, & Lagacé, 1994; Van Bressem, Waerebeek, Piérard, & Desaintes, 1996). Furthermore, the penis presents a cavernous, spongy corpus, and it was possible to describe the penis retractor muscle; similar data have been obtained in other cetaceans and marine mammals (Matthews, 1950; Ross & Pawlina, 2011; Slijper, 1996).…”

Section: Discussionsupporting

confidence: 56%

“…However, studies on gonadal development and reproductive morphology have been performed in other cetaceans (Matthews, 1950; Ross & Pawlina, 2011; Slijper, 1996). To our knowledge, studies of the Clymene dolphin are scarce in the scientific literature and have mainly involved Stenella clymene .…”

Section: Introductionmentioning

confidence: 99%

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Morphological description of the male reproductive tract of the Clymene dolphin (Stenella clymene, Gray, 1850)

et al. 2020

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Stenella clymene is an endemic species of dolphin living in tropical regions in the Atlantic Ocean. Despite its wide distribution, there is still scarce information on Stenella clymene, including its reproductive biology. In this context, this work describes the morphology of the whole male reproductive tract of the Clymene dolphin. Five males (N = 5) were studied after stranding on the northeast coast of Brazil. The analysis was performed through the use of macroscopic techniques and light and scanning microscopy. The male reproductive system consists of large testes wrapped around the tunica albuginea and adhered to the epididymis; the testes are attached to the abdominal cavity by the mesorchium. The ductus deferens is convoluted in the proximal portion and rectilinear in the distal portion. The prostate was the only accessory gland found, which is submerged by the prostate compressor muscle and lined with a dense fibroelastic capsule. The penis is classified as fibroelastic, with a spiral sigmoid flexure associated with a large volume of muscle tissue. The penis is inserted into two vestigial bones or pelvic bones, which exhibit no connection with the spine. In conclusion, the macro‐ and microscopic conformation and other morphofunctional features of the male reproductive organs of Stenella clymene are in accord with the anatomy observed in other Cetartiodactyla.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 56%

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Morphological description of the male reproductive tract of the Clymene dolphin (Stenella clymene, Gray, 1850)

et al. 2020

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“…The cetacean penis is fibroelastic; erectile tissue is filled with collagen and elastin fibres instead of the spongy tissue found in the vascular penis of most mammals [27]. Thus the cetacean penis is generally maintained in a turgid state within the body cavity and distends further with an influx of blood into the erectile tissue [27]. The penis in cetaceans does not have an inflatable terminal glans, but in some species it ends in a terminal cone ( pars intrapreputialis; [27]; figure 1).…”

Section: Introductionmentioning

confidence: 99%

Genital interactions during simulated copulation among marine mammals

2017

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Genitalia are morphologically variable across many taxa and in physical contact during intromission, but little is known about how variation in form correlates with function during copulation. Marine mammals offer important insights into the evolutionary forces that act on genital morphology because they have diverse genitalia and are adapted to aquatic living and mating. Cetaceans have a fibroelastic penis and muscular vaginal folds, while pinnipeds have a baculum and lack vaginal folds. We examined copulatory fit in naturally deceased marine mammals to identify anatomical landmarks in contact during copulation and the potential depth of penile penetration into the vagina. Excised penises were artificially inflated to erection with pressurized saline and compared with silicone vaginal endocasts and within excised vaginas in simulated copulation using high-resolution, diffusible iodine-based, contrast-enhanced computed tomography. We found evidence suggestive of both congruent and antagonistic genital coevolution, depending on the species. We suggest that sexual selection influences morphological shape. This study improves our understanding of how mechanical interactions during copulation influence the shape of genitalia and affect fertility, and has broad applications to other taxa and species conservation.

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“…The tips of the horns of the nonpregnant uterus curves in the caudal direction. Both the tip and the base of the uterine horn are fixed to the abdominal wall at a point not far cranial of the pelvic bone [ 18 ]. Therefore, range of movement of the uterus will be limited by these ligamenta.…”

Section: Discussionmentioning

confidence: 99%

Embryo and fetal position during pregnancy by ultrasonographic examinations in bottlenose dolphin (<i>Tursiops truncatus</i>)

Terasawa

Akiyama

Sakuragi

et al. 2021

The Journal of Veterinary Medical Science

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From 2012 to 2017, serial ultrasonographic evaluation of 5 healthy bottlenose dolphins, Tursiops truncatus, were performed over the course of 6 pregnancies in Enoshima Aquarium. A total of 98 ultrasonographic examinations were included in the study. In three out of six cases, two embryos were observed between umbilicus and genital slit, and side of umbilicus in the dam's body. All embryos were located in right below the peritoneum and observed from 308 to 325 days pre-partum. These days were corresponding to from 58 to 61 days after copulation respectively. The diameter of the embryo sac was approximately 4 cm. In three cases, the fetal head was located in the dam's left lateral between umbilicus and genital slit from approximately 90 days prepartum to the parturition. A snout of fetus is at the top of the uterine horn, and the tail lies close to the cervix. All six calves were fluke-first births (breech presentation). It was conjectured that the contraction of the dam's uterus during parturition forced the fetus to invert, and the fetal tail fluke was expelled from the dam's body. In three cases, judging from orientation of fetal tail fluke faced towards left side of the dam, a fetal position might be RSL (Right Sacrum-Lateral) within the birth canal. In the other three cases, the left and right positions of the fetus and the dam's body are reversed during pregnancy and parturition.

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15. Functional Morphology of the Reproductive System in Cetacea

Cited by 38 publications

References 0 publications

Morphological description of the male reproductive tract of the Clymene dolphin (Stenella clymene, Gray, 1850)

Morphological description of the male reproductive tract of the Clymene dolphin (Stenella clymene, Gray, 1850)

Genital interactions during simulated copulation among marine mammals

Embryo and fetal position during pregnancy by ultrasonographic examinations in bottlenose dolphin (<i>Tursiops truncatus</i>)

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