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.
