Morphology and Morphometry of the Ovaries and Uteri of the Amazonian Freshwater Stingrays (Potamotrygonidae: Elasmobranchii)

Abstract

The reproductive biology of South American freshwater stingrays (family Potamotrygonidae) is still poorly studied compared to other marine species. In the present study, we examined the gross anatomy and histology of six species of potamotrygonids from the Amazon basin and described the structural asymmetry of the ovaries and their relationship between ovarian and uterine fecundities. Stereological techniques were used to quantify the volume of ovarian and epigonal organ tissue associated with the left and right sides of the Potamotrygon wallacei, a recently described species, locally known as the cururu ray. This species presented ovarian asymmetry; the left epigonal organ-ovary complex was 55 times larger than the right side. The right side was composed of, volumetrically, 7.3% ovarian tissue and 92.7% epigonal organ tissue whereas the left side was 51.2% of ovarian tissue and 48.8% epigonal organ tissue. In all species, six types of follicles were identified in both right and left ovaries. Uteri were symmetrical and the fecundity ratio between the right and left sides was 0.9:1.1, respectively. Despite the volumetric difference of ovarian tissue between the two sides, the uterine fecundity shows that both ovaries are functional and that ovarian fecundity alone is not an accurate measure to determine the reproductive potential of freshwater stingrays. Anat Rec, 300:265-276, 2017. © 2016 Wiley Periodicals, Inc.

Microanatomy of the female reproductive system of the viviparous freshwater whipray Fluvitrygon signifer (Chondrichthyes: Myliobatiformes: Dasyatidae). II. The genital duct

“…The myometrium of the chondrichthyan uterus consists of combinations of the muscular organization that have been classified into six patterns: (1) the inner circular and outer longitudinal muscle fibers, as in the rays, G. poecilura [ 39 ], P. aiereba , P. iwamae , P. motoro , P.orbignyi , P. schroederi , P. scobina , P. wallacei [ 41 ], P. bleekeri [ 6 , 78 ], P. magdalenae [ 42 ], and F. signifier ; the sharks, M. griseus , M. manazo [ 50 ] M. schmitti [ 69 , 81 ] and Scoliodon laticaudus (formerly S. sorrakowah ) [ 9 ]; the skates, S. acuta and Sympterygia bonapartii [ 14 ]; the ratfish, H. colliei [ 20 ] and the guitar fish, R. lentiginosus [ 47 ]; (2) the inner longitudinal and outer circular muscles, as described in the rays, A. nichofii [ 78 ], B. walga [ 82 ] and L. erinacea [ 73 ]; (3) three muscular tunics with a diagonal muscle layer as the outermost layer in the shark, I. omanensis [ 70 ]; (4) three muscular layers with the circular musculature intercalated between two layers of the longitudinal musculatures in R. terraenovae [ 83 ]; (5) three muscular layers, with the longitudinal muscle layer inserted between the inner and outer circular muscle layers, as in S. tiburo [ 74 ] and the topeshark, H. japonica [ 63 ]; and (6) uniquely in Mustelus schmitti having three muscular tunics: inner reticularly-orientated muscle, middle and outer longitudinal muscles [ 69 ]. Interstitial spaces in the myometrium of some specimens may accommodate imbibed water that is correlated with reproductive events, as proposed in the southern eagle ray, Myliobatis goodei [ 40 ].…”

“…The microanatomical structures of the ovary of F. signifer has been recently described [ 34 ], but those of the female genital ducts have not been reported. As far as is known, basic knowledge on the microscopic structures of the myliobatiform female genital ducts has been gathered from several studies of various species belonging to different families, including three marine urotrygonids [ 15 , 35 – 38 ], one marine gymnurid [ 39 ], one marine myliobatid [ 40 ], seven freshwater potamotrygonids [ 41 , 42 ], one marine rhinopterid [ 43 ] and four marine dasyatids [ 6 , 17 , 35 , 44 , 45 ]. However, detailed histological and histochemical descriptions of the entire genital ducts and information on body morphometrics related to maturity statuses from a single species are still not available.…”

Sperm competition, sexual selection and the diverse reproductive biology of Osteoglossiformes

“…Nurse sharks ( Ginglymostoma cirratum) develop only one ovary on the right side of the body (Castro, 2000). Amazonian freshwater stingrays ( Potamotrygon wallacei ) have two functional ovaries, but the left ovary is 55 times larger than the right ovary (da Silva et al ., 2017). The presence of ovarian asymmetry in both Chondrichthyes and Osteichthyes suggests that this primitive trait may go as far back as the Gnathosomes.…”

Female reproductive traits of a commercially exploited skate: Atlantoraja platana (Günther, 1880) (Chondrichthyes, Rajidae). Ovarian morphology, gametogenesis and microscopic verification of maturity criteria

“…To evaluate reproductive potential and reproductive success, fish females are usually examined with macroscopic and morphometric tools, such as ovaries size and texture, oocytes color and size, uteri wide and oviductal gland development (Stehmann, 2002;Serra Pereira et al, 2011) and recently by histologic analysis. This last approach is actually considered the most accurate means to assess gonadal development in fish, by identifying the presence of vitellogenic follicles, sperm storage in oviductal gland, atresia and ovarian fecundity, among other features (Alonso Fernandez et al, 2011;Da Silva et al, 2017;Henderson et al, 2014;Moura et al, 2011;Waltrick et al, 2017).…”