Plasma arginine vasotocin, progesterone, and luteal development during pregnancy in the viviparous lizard Tiliqua rugosa

Hormonal Regulation of Ovarian Function in Reptiles

“…The steroidogenic enzyme 3b-HSD, which converts pregnenolone to P 4 , is detectable in luteinized granulosa cells by histochemistry. Luteolysis (Fox & Guillette, 1987;Fergusson & Bradshaw, 1991), luteectomy (Highfill & Mead, 1975;Guillette & Fox, 1985), or ovariectomy (Fergusson & Bradshaw, 1991) are associated with a marked drop in plasma P 4 concentrations as the luteal cells lose their capacity to secrete P 4 or the source of that P 4 is removed. Callard et al (1992) distinguished two basic patterns of P 4 secretion in reptiles.…”

Birthing asynchrony is not a consequence of asynchronous offspring development in a non‐avian vertebrate, the Australian skink Egernia whitii

“…However, females not only give birth asynchronously, but do so to offspring within an oviduct (female reptiles have two oviducts (Norris 1997) and in litters of three, first‐, second‐ and third‐born offspring are all born separately), suggesting sophisticated site‐specific effects of circulating AVT or a mechanism by which birth parturition of all embryos is deferred at the birth of the first. Interestingly, in a closely related skink, Tiliqua rugosa , plasma AVT rises well before parturition, suggesting such a mechanism preventing parturition until the appropriate time exists (Fergusson & Bradshaw 1991). In addition, we do not know to what extent the embryos control the onset of parturition.…”

Hormones and the Sex Ducts and Sex Accessory Structures of Reptiles

“…Arginine vasotocin, a potent stimulator of oviductal contractions (Ewert & Legler, 1978;Mahmoud, Cyrus, McAsey, Cady, & Woller, 1988), is most effective if given late in pregnancy (viviparous forms) or during the gravid period (oviparous forms) (Mahmoud et al, 1988;Guillette, DeMarco, Palmer, & Masson, 1992). Prostaglandin F 2a concentrations in the blood of sea turtles (Guillette et al, 1991c), the tuatara (Guillette et al, 1990a), and the lizard Tiliqua rugosa (Fergusson & Bradshaw, 1991) are all elevated at the time of oviposition. Further, indomethacin, an inhibitor of prostaglandin synthesis, can delay parturition in this same species (Guillette et al, 1991a).…”