Comparison of the first mitotic cell division in French Rainbow trout (Oncorhynchus mykiss) embryo and existing brood stock in Ardebil

This study was carried out to determine the first mitotic interval or First Cleavage Interval (FCI) between French origin and the brood stocks existing in Ardabil to adjust the shock induction time. In addition, the aim was to maximize tetraploid induction and increase the survival rate of shock-treated larvae. To this end, two groups of eggs, brood stocks of French origin and the brood stocks existing in Ardabil were used. Seven hours after fertilization with intervals of 10 minutes to 10 hours, 10 eggs were sampled. This was repeated after each fertilization. Prior to transportation of samples to the lab, they were fixed using Davidson fixative solution. Time interval or the FCI was considered the time that 50% of the eggs reached the cleavage stage. The FCI was determined through microscopic analysis of the eggs and was identified as the time at which the midline appeared in the embryo. After examining the samples, the average FCI for the French race was determined to be 560 minutes after the fertilization; whereas, this time for the brood stocks existing in Ardabil was 570 minutes.