Great Ball of Fire

What am I looking at?

This is a tissue sample from a zebrafish heart and its surrounding tissues. The golden strands are the muscle cells (1) that make up the ventricle of its heart. The surrounding blue dots are the nuclei of the tissue around the heart (2).

Biology in the background

The heart is mainly made up of muscle tissue that pushes blood throughout the body. In mammals, including humans, this muscle is divided into four chambers: two ventricles and two atria. The atria have thin walls and receive blood from veins throughout the body. The ventricles have thick walls and are responsible for forcefully pushing blood out of the heart to the rest of the body.

But the heart of a fish has only two chambers: one atrium and one ventricle. However, the heart of a zebrafish (like the one shown here) has a unique ability to regenerate damaged or destroyed heart tissue, which makes the zebrafish a great organism in which to study potential treatments for heart disease and injury.

A zebrafish heart is about 1 millimeter across, or roughly 13 times larger than the width of a human hair.

Technique  

This image was created using fluorescence microscopy.