Effect of exogenous estradiol on the gross morphology and morphometry of the male chicken (Gallus domesticus) gonads

Abstract

Estrogen plays a key role during gonadal differentiation of female chickens. Embryonic exposure to exogenous estrogens had shown a temporary feminization of the male gonads. Therefore the current study was aiming at finding out the feminizing effects of post-hatching continuous exogenous estrogen supply to the gross morphology and the morphometry of in-ovo estrogen treated male chicken gonads with age. Shaver brown chicken eggs were incubated under standard conditions and two in-ovo injections of 20ul of 5mg/ml estradiol cypionate per egg were given to each treated egg and same volume of PBS were injected to control eggs. The male chicks hatched (9 Control and 18 treated) were raised for 2 months feeding according to the feeding schedule given in the “Shaver Brown Management Guide” (Netherland). A half (9) of treated chicks were given with a weekly post-hatching injection of 0.1ul/ chick estradiol cypionate intra muscularly (T2) and the rest (9) were raised with no post-hatching injection (T1). 3 chicks from each group including control (C) were sacrificed at 1 week, 4 weeks and 8 weeks intervals and gross morphology and the morphometric measurements were recorded. T1 and T2 chicks showed well-developed and lobulated left gonad which was similar to control female. However the right gonad showed a significant difference between T1 and T2 where T1 chicks showed a very fragile and poorly developed right gonad while T2 showed a prominent right gonad which was similar in color and texture of control male gonads. The weights of both right and left gonads showed significant difference only at the 8th week (P=0.0199 and P=0.0257) while the width of the left gonad at 1st and 8th weeks showed a significant difference (P=0.0318 and P=0.049respectively). In conclusion, male chicken gonads are feminized with embryonic estradiol exposure and the continuous exposure leads to development of the right gonad along with the feminized left gonad.