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In fish, sharks and amphibians, a long vascular system extending from the gills supplies blood to the heart.  By contrast, in mammals and birds, this ancestral vasculature exists only during the embryo stage and later transforms into adult coronary arteries which are wrapped around the heart. This evolutionary change is likely connected to the transition of vertebrates from water to land, which led to the loss of gills," explained researcher Hiroki Higashiyama from the Department of Physiological Chemistry and Metabolism at the Graduate School of Medicine at the University of Tokyo. Amphibians sit in between fish and mammals on the evolutionary tree and so may offer some insight as to how one type of heart evolved into the other. "As an example, we saw that the transient blood vessels observed in mice embryos bore a striking resemblance to the ancestral vascular system found in amphibians," said Higashiyama. "As the mouse's coronary arteries form, these ancestr...

  CHD refers to a range of issues, including anomalous coronary artery, where the coronary arteries are malformed.  These arteries supply the heart with oxygenated blood, so if they are not properly developed then it can cause sudden and dangerous complications. But not all species have this problem. There are animals including fish and amphibians whose hearts don't have or need coronary arteries. So why do we and where did they come from? To help answer these questions, researchers in Japan compared the development of blood vessels in the hearts of mice, Japanese quails, newts, zebrafish, sharks and frogs. The work is published in the journal eLife. The team used a combination of techniques, including MRI, micro-CT scans, sectioning (analyzing thin slices of the hearts under a microscope) and 3D reconstruction, to create detailed images. By comparing these images, they could see the difference in how the blood vessels (vascular system) develop in the hearts of amniotes, i.e.,...