Until now, limited research on embryos has prevented scientists from understanding how maternal use of alcohol causes congenital heart defects. A new imaging technique, known as optical coherence tomography, provides new insight.
Optical coherence tomography, or OCT, is similar to an ultrasound except that an OCT uses light waves rather than sound to create an image. An OCT also returns high-resolution, three-dimensional images on a micron scale that allows scientists to capture cross-sectional images on tiny, beating embryo hearts.
To avoid using human embryos, researchers from Case Western Reserve University used OCT on quail embryos because heart development is similar between the two species. The researchers exposed test quail embryos to a single, large dose of alcohol by injection through the shell. The dose was equivalent to the amount of alcohol consumed by a pregnant woman on a drinking binge. The scientists then compared OCT images of test subjects’ hearts to those of quail embryos that did not receive an alcohol injection.
For this study, the scientists focused their work on a particular developmental stage, known as gastrulation, in which birth defects tend to develop. Gastrulation happens in the first few days after ovulation when the embryo is still a tiny ball of cells but events that occur during this developmental stage can have lasting effects.
During gastrulation, the embryo heart transforms from a tube-shaped organ to a loop-shaped circuit, changing blood flow within the embryo’s body. Heart cells are especially sensitive to blood flow during the earliest stages of development. Poor heart function in developing embryos sets the stage for large defects to occur later in development. Using OCT, the scientists found the quail embryos exposed to alcohol showed signs of altered blood flow and heart anatomy.
Comparing blood flow and heart anatomy during gastrulation can help scientists link maternal alcohol consumption with the birth defects doctors could expect to find in developed hearts. The researchers noted the exposed quail embryos showed signs of birth defects near the time of hatching, such as thin walls between the heart’s four chambers and damaged valves. Defects like these are often the result of blood flowing in the wrong direction.
This study underscores the need to gain a better understanding of fetal alcohol syndrome.
Source: MacGill, Markus. "How alcohol leads to birth defects - clues from embryo heart images." Medical News Today. MediLexicon, Intl., 4 Jan. 2014. Web.19 Jan. 2014.