Steroid production by maternal and embryonic, issues in a viviparous lizard demonstrate the potential for embryo-maternal signalling

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

Congreso; International Conference of Comparative Physiology and Biochemistry; 2011

Hormones have important organisational and activational roles during embryonic development. These hormones mayhave maternal or embryonic origins. In viviparous (live-bearing) vertebrates, the embryo is exposed to maternal hormonesvia the placenta, which forms an interface between maternal and embryonic endocrine systems. We examined steroidproduction by embryonic and maternal tissues in the viviparous lizard Niveoscincus ocellatus. We hypothesised thatpatterns of steroid production would vary between tissues, with embryonic stage, and between different temperatures inthis ectothermic species.Females were collected in mid/late gestation and sacrificed. Embryos were removed and staged. Their adrenals andgonads were incubated at 16° or 28°C for three hours, with or without the steroid precursor pregnenolone; in youngerembryos, the entire embryo trunk was incubated. Maternal tissues (oviduct, placenta, corpus luteum, non-luteal ovary, andmuscle = non-endocrine control tissue) were incubated at 16° or 28°C with or without pregnenolone. Incubation mediawere assayed for testosterone, progesterone, estradiol and corticosterone using radioimmunoassay. The corpus luteumproduced the most progesterone, but placenta and uterus were also steroidogenic. Adrenals of late stage embryosproduced significant corticosterone: production was greatest at 28°C, with pregnenolone. These results suggest thepotential for maternal-embryo endocrine signalling in a viviparous reptile.