Reproduction, placentation, and embryonic development of the Atlantic sharpnose shark, Rhizoprionodon terraenovae

Abstract

The Atlantic sharpnose shark Rhizoprionodon terraenovae (Richardson) is a small carcharhinid that is a common year-round resident along the southeast coast of the United States. It is viviparous and its embryos develop an epithelio-vitelline placenta. Females enter shallow water to give birth in late May and early June. Mating occurs shortly after parturition, and four to seven eggs are ovulated. Fertilized eggs attain the blastoderm stage in early June to early July. Separate compartments for each egg are formed in the uterus when the embryos reach 3-30 mm. Embryos depend on yolk for the first 8 weeks of development. When embryos reach 72 mm their yolk supply is nearly depleted and they shift to matrotrophic nutrition. When the embryos reach 40-55 mm, placental development begins with the vascularization of the yolk sac where it contacts the uterine wall. Implantation occurs at an age of 8-10 weeks by which time the embryos reach 70-85 mm. The expanding yolk sac engulfs the maternal placental villi, and its surface interdigitates with the villi to form the placenta. The rest of the lumenal surface of the uterus is covered by non-placental villi that appear shortly after implantation. Histotrophe production by the non-placental villi begins just after their formation. The placenta grows continuously during gestation. The egg envelope is present throughout gestation, separating maternal and fetal tissues. Embryos develop numerous appendiculae on the umbilical cord. Young sharks are born at 290-320 mm after a gestation period of 11 to 12 months. © 1993 Wiley-Liss, Inc.

Reproductive biology and diet of the grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhinidae) from the north-eastern Arabian Sea

“…The observation of R. oligolinx females simultaneously carrying term embryos and vitellogenic follicles indicates an annual reproductive cycle with concurrent ovarian and gestation cycles. This aspect has also been observed for other Rhizoprionodon species (Parsons, 1983;Stevens and Mcloughlin, 1991;Simpfendorfer, 1992;Castro and Wourms, 1993;Motta, et al, 2005). In this study, we observed ovarian fecundity and uterine fecundity ranging from 2 to 6 follicles (mean = 4) and from 1 to 7 embryos (mean=4.1) respectively.…”

Reproductive biology of the school shark, Galeorhinus galeus, off Argentina: support for a single south western Atlantic population with synchronized migratory movements

“…In contrast, the pattern of embryonic development appears to be more variable. Linear growth was suggested for embryos of the blue shark, Prionace glauca (Pratt 1979); a von Bertalanffy-like growth pattern for embryos of the Atlantic sharpnose shark, Rhizoprionodon terraenovae (Parsons 1983, Castro & Wourms 1993 and the blacktip shark, Carcharhinus limbatus (Castro 1996); and a sigmoidal Gompertz-like pattern for embryos of the finetooth shark, Carcharhinus isodon (Castro 1993). The data on school shark embryonic growth presented here fit a Gompertz curve (Figure 10b).…”

Gestational morphogenesis of the uterine epithelium of the gummy shark (Mustelus antarcticus)

“…These characteristics include similar follicle diameters at ovulation; development of uterine compartments; similar oviducal gland structure; similar gestation periods of 10-12 months; retention of the egg envelope throughout gestation; similar egg envelope structure; similar embryo size at birth; similar mass gain from mature egg to full-term embryo; and no internal yolk sac at birth (e.g. Gilbert and Schlemitzauer, 1966;Pratt, 1979;Baranes and Wendling, 1981;Castro and Wourms, 1993;Graham et al, 1995;Hamlett and Koob, 1999;Conrath, 2000;Conrath and Musick, 2002;Hamlett et al, 2005a).…”

“…Each embryo develops in its own compartment and the orientation of each compartment changes from oblique to longitudinal throughout gestation in preparation for birth. The development of these compartments increases the effective surface area for metabolic exchanges and prevents abrasion or entanglement of yolk stalks or umbilical cords (Parker, 1882;Alcock, 1890;Ranzi, 1934;TeWinkel, 1963;Gilbert and Schlemitzauer, 1966;Teshima and Mizue, 1972;Chen and Mizue, 1973;Teshima and Koga, 1973;Appukuttan, 1981;Teshima, 1981;Koob and Callard, 1991;Castro, 1993;Castro and Wourms, 1993;Hamlett et al, 1993b;Joung and Chen, 1995;Hamlett and Hysell, 1998b;Hamlett and Koob, 1999;Chen et al, 2001).…”