production by maternal and embryonic tissues in a viviparous lizard

JONES, S. M.; AWRUCH C. A.

Congreso; 2012 World Congress of Herpetology; 2012

World Congress of Herpetology

Hormones have important organisational and activational roles during embryonic development. These hormones may have maternal or embryonic origins. In viviparous (live-bearing) vertebrates, the embryo is exposed to maternal hormones via the placenta, which forms an interface between maternal and embryonic endocrine systems. Environmental influences on the maternal endocrine system may therefore be transmitted to the embryo. We examined steroid production by embryonic and maternal tissues in the viviparous lizard Niveoscincus ocellatus. We hypothesised that patterns of steroid production would vary between tissues, with embryonic stage, and between different temperatures in this ectothermic species. 352 Females were collected in mid to late gestation and sacrificed. Embryos were removed and staged: samples were allocated to groups according to embryo stage (Stage 30-37; Stage 39 or Stage 40 = prebirth). Their adrenals and gonads were incubated at 16° or 28°C (species? preferred body temperature) for three hours, with or without the steroid precursor pregnenolone; for younger embryos, the entire embryo trunk was incubated. Maternal tissues (oviduct, placenta, corpus luteum, non-luteal ovary, and muscle = non-endocrine control tissue) were also incubated at 16° or 28°C with or without pregnenolone. Incubation media were assayed for testosterone, progesterone, estradiol and corticosterone using radioimmunoassay. Of the maternal tissues, the corpus luteum produced the most progesterone, with greater production in the presence of pregnenolone (F1, 48=89.85, P