Meeting Abstract

P3.85  Wednesday, Jan. 6  Age- and sex-specific uptake and distribution of yolk androstenedione in chicken (Gallus gallus) embryos HODGE, Melissa G.*; BENOWITZ-FREDERICKS, Morgan; Bucknell University; Bucknell University mgh010@bucknell.edu

Steroid hormones transferred from avian females to the egg yolk of their offspring affect multiple aspects of hatchling phenotype. However the location and timing of the effects in embryos are essentially unknown. Androstenedione is found in large quantities in egg yolk and is often manipulated in experimental studies of avian maternal effects. Androstenedione is often assumed to be converted into the sex steroids testosterone and estrogen, however almost nothing is known about its uptake and use by embryos. We explored the tissue-specific distribution of tritiated androstenedione that was injected into fresh eggs in male and female chicken (Gallus gallus) embryos. Tritium was quantified in head, body, and yolk of day 7 embryos and in blood, brain, liver, heart, muscle, and yolk of day 16 embryos. Tritiated hormone was found in all tissues analyzed, but at both days 7 and 16 the majority of tritiated hormone was extra-embryonic. There were no significant differences between day 7 embryonic tissues. On day 16, the concentration of tritiated hormone was higher in female brains, but there was no difference in other tissues. Liver tissue from day 16 embryos contained significantly higher concentrations of tritiated hormone than all other tissues. While sex and tissue specific metabolism of androstenedione into active sex steroid derivatives remains to be investigated our study shows that yolk-derived androstenedione is present in all tissues of developing embryos. Thus, maternal androstenedione is likely an important component of avian endocrine maternal effects.