In-Vivo PIV Measurement Of The Blood Flow In The Heart And Main Vein Of Medaka Embryo

In order to examine the generation mechanism of the vertebrates, including humans, and to explore the diverging point of the genetic abnormalities, it is effective to investigate the growth of the embryo of an artificial mutant. As the embryos of Medaka hatch outside of the body and their egg membrane are transparent, it is quite easy to carry out the in-vivo observation of their organs. Moreover, the development and the structure of their major organs of Medaka are quite similar to those of human. Thus, the observation of the developmental abnormalities of Medaka embryos may serve as a clue to the pathologic investigation of the genetic disease and hopefully give some insight to the future effective treatment. Presently, the intracardiac blood flows of Medaka embryos have been observed by a high-speed camera under microscope. The obtained images are pre-processed and the velocity fields in the heart and in the main vein of Medaka embryo are measured by PIV method. The red blood cells flowing inside the heart and in the main vein of Medaka embryos are used as tracer particles. The image pre-processing was applied to capture the image of red blood cells and then the cross-correlation method can be applied. As a result, it is found that the velocity defect caused by the valve closing is clearly observed in the main vein and the amplitude of the velocity defect is decreasing with the distance to the heart. It is also found that the beating of the heart corresponds to the pulsatio of the flow velocity of the red blood cell in the heart. In conclusion, the authors observed the Medaka embryo under microscope with a high-speed camera and measured the velocities of the red blood cells in the heart and in the main vein by PIV measurement using the pre-processed images.