The effects of testosterone and corticosterone treatment on gene expression in germinal discs of the laying hen

Previous work has suggested that the hormones testosterone and corticosterone influence the process of meiotic segregation in the ovarian follicles of laying hens, ultimately influencing whether the resulting egg produces a male or female chick. We tested whether treatment with testosterone and/or corticosterone stimulated changes in the expression of genes that may influence the process of meiotic segregation as a next step towards understanding the mechanism by which these hormones may play a role in sex ratio adjustment in birds. Overall design: Five biological replicates were performed. Each replicate contained pooled samples from 8 individual hens. Hens were treated with either corticosterone (1.5mg in 0.5ml peanut oil), testosterone (1.5mg in 0.5ml peanut oil) or control oil (0.5ml peanut oil) at 5h prior to expected ovulation (as predicted according to previous laying cycles). Hens were killed via lethal injection 1.5h after injection (3.5h before ovulation) and germinal discs were collected from F1 follicles to determine whether expression of genes that control chromosome segregation was influenced by either or both of the two treatments.