Comparison of gonadal hormone levels in turkey embryos incubated in long-term shell-less culture and in ovo

Changes in concentrations of 17 beta -estradiol (E-2) and androgenic hormon es were measured in turkey embryos incubated in long-term, shell-less cultu re lex ovo) and in ovo. Blood samples were obtained from both sets of embry os on Days 14, 16, 18, 20, and 22 and from embryos incubated in ovo on Days 24, 26, and 28. Ex ovo and in ovo embryos showed no differences in either hormone within sexes, with one exception. On Day 14 of incubation, the ex o vo females had higher (P < 0.05) E-2 levels (55.6 +/- 5.1 pg/mL) than the i n ovo females (32.2 +/- 2.3 pg/mL); however, this result might have been du e to the small sample size (n = 3) for ex ovo females. No significant diffe rences were found in androgen concentrations between sexes in ovo on Days 2 4, 26, and 28 of incubation. However, on Days 24, 26, and 28, in ovo female s showed highly significant differences (P < 0.01) in E-2 compared with mal es of the same age. These results indicate a similar developmental pattern for the endocrine system in ovo and ex ovo through Day 22 of incubation. Fu rther, there were sex differences in E-2 that are likely to be critical for sexual differentiation that emerges late in embryonic development.