112. Differential Development of Sex-Related Characters of the GSP and PNP/Do Chickens After Left-Ovariectomy

Abstract

To elucidate the strain difference in the sex reversal of genetic female to phenotypic male, GSP and PNP/DO females were left ovariectomized (ovx) between one day to three days after hatching and the degree of masculinization based on sex-related characters, histological analysis of the right gonad and hormone assay were assessed at one year of age. The GSP and PNP/DO inbred lines were both derived from the Fayoumi breed and are only differentiated based on red blood cell antigens type carried by each of the inbred line. Comb and wattles were found to be significantly bigger (P < 0.05) in the GSP ovx compared to the PNP/DO ovx, although male plumage pattern were more pronounced in the PNP/DO ovx. Spurs were observed both in the GSP and PNP/DO ovx with no significant difference (P > 0.05) in length to the respective male controls and body weight were not significantly different (P > 0.05) to the female controls. The size of the right gonad were significantly bigger (P < 0.05) in the GSP ovx than the PNP/DO ovx. Positive correlations were found in the sex related characters as well as plasma testosterone level and the right gonad weight both in the GSP and PNP/DO ovx except for the spur length which resulted into a negative correlation in the PNP/DO ovx. Histological analysis revealed that the right gonad of PNP/DO ovx are morphologically developed compared to GSP ovx showing more advance stages of spermatogenesis. It could be inferred that PNP/DO females which exhibit hereditary persistent right oviduct, are more responsive to the masculinizing effect of ovariectomy compared to GSP females, suggesting that genetic background may have a possible contribution on the degree of masculinization and subsequent development of sex related characters.

Sex Reversal in Birds

“…In one strain of chickens, removal of the left ovary after hatching (ovariectomy) induces the small female spur to enlarge and lengthen so that it resembles that in a male, while in another strain, it does not [Valdez et al, 2010]. Differences in body mass between the sexes may be under direct genetic control, as body mass conforms to genetic sex even when sex hormone levels are experimentally manipulated, at least in chicken [Valdez et al, 2010;Lambeth et al, 2016a].…”