Timing of the Ovariectomy Operation Effects the Survival of Newly-hatched Chicks

Preliminary experiments performed in our laboratory on orthotopic transplantation of the ovarian tissue in newly-hatched chicks demonstrated that majority of chicks could not survive the surgical technique described by Song and Silversides (2006) and die within 24 h following the operation. A series of experiments were performed in the present study to determine underlying causes of this high mortality rate. A total of 50 newly-hatched chicks (day 0) went through the operation in the first series of experiments. It was determined that the survival rate did not exceed 36% and majority of chicks died within 24 h following the operation in agreement with our preliminary observations. The effect of the removal of the yolk sac on various time points in reference to the day of hatching was examined in a second series of experiments. When the yolk sac was removed on the day of hatching (n=10, day 0), only 30% of the chicks survived the operation. When the yolk sac is removed either on day1 (n=11, 24 h post-hatch) or on day2 (n=8, 48 h post-hatch) 73 and 100% of chicks survived the operation, respectively. These results suggest that the orthotopic transplantation of the ovarian tissue in the chick should be performed one or two days following the day of hatching to avoid the high mortality rate associated with the surgical technique.