Wellcome Image of the Month: The shape of the heart
Forget cutesy cartoon-shaped hearts this Valentine’s Day, our image of the month reveals the true shape of the heart. This picture of a mouse embryo was created by Dr Laura Pastorelli during her time working as a Research Assistant at the MRC National Institute for Medical Research (NIMR). She has since hung up her lab coat and is the Biomedical Images Coordinator at Wellcome Images. In the interview below, she explains more about this striking image.
What exactly are we looking at here?
This is a developing mouse embryo. It’s 10.5 days old here, and is stained using a technique called immunohistochemistry. This uses antibodies with fluorescent dyes attached. Different antibodies bind to different proteins, so using a particular antibody can highlight where a particular protein is expressed.
In this case, staining using MF20 antibody highlights striated muscle, which is formed from long fibres and includes both skeletal muscle and cardiac muscle. MF20 staining shows up in red here, and highlights the heart and the somites. The somites will go on to form skeletal muscle, and can be seen running along the spine of the embryo.
The heart is shown here at the ‘looping stage’. The organ initially develops as a single tube before looping round itself. At a later stage in development, the heart tube will fuse to form the four chambers of the heart.
How exactly was this image made?
It was created using a technique called optical projection tomography (OPT). When I started working at the NIMR, this technique was very new and the lab I was working in had just received a prototype OPT machine. Dr Tim Mohun, Head of the lab, wanted me to develop the method so that the OPT could be used to study heart development, the lab’s research focus.
When investigating structural detail, normally, samples are sliced before being stained and imaged. This isn’t great, because the act of slicing normally distorts the delicate structures of the sample. OPT allows whole specimens to be imaged non-invasively so all the structures remain intact. It allows scientists to track the development of these tissues in situ and relative to other structures. In the image here, we can see the position of the heart in relation to the rest of the embryo.
What else is special about this technique?
It’s incredibly accurate. When a sample is imaged, it’s mounted on a magnetic block and rotated through 360 degrees. Around 400 images are taken throughout the process, which are reconstructed using a computer program to make a 3D movie of the sample. This image is a still from one of those movies.
The image itself has had colours added to emphasise the staining, the original image comes out in greyscale.
What’s important about the image?
The problem with imaging hearts is that they’re made up of thick, muscular tissue and it’s hard to get stains to penetrate into the deeper regions of the tissue. So the staining often ends up stuck to the surface of the heart, and you don’t get a picture of the whole structure. When I took this image, I was working on a method to get the antibody stain deep into the embryo, and this was one of the few successful attempts.
How does it feel to be both in charge of acquiring new pictures for Wellcome Images, and being the creator of a Wellcome Image of the Month? We should note that because your name isn’t in the credit line, we didn’t realise you were the creator of the image at first!
I was working for the MRC at the time so the credit line reflects this but having personally produced this image it is nice to see it has been selected. I’ve always been fascinated by developmental biology. It’s amazing how the fusion of two cells in one single event during fertilisation can develop into something so complex. Having a Wellcome Image of the Month that conveys this interest is great. That said, I acquire so many fantastic images from a number of different fields and its always interesting to find out more about the research that’s going on and to see the range of images that are being produced by other scientists.
All the biomedical images acquired by Wellcome Images are eligible for consideration for a Wellcome Image award. In two weeks time, the winners of the Wellcome Image Awards 2011 will be announced. The awards recognise the most visually striking, technically excellent and informative pictures recently acquired by Wellcome Images. You can read a post about this year’s judging process on the Wellcome Library blog.
Louise Crane, Picture Researcher, Wellcome Images
Image credit: NIMR, MRC/Wellcome Images