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This video is made in partnership with Nikon Healthcare, a leader in scientific imaging and tools.

You can learn more about their imaging technology and microscopy solutions by visiting the link in the description. In labs around the world, you can find tanks like this one.

They are filled with zebrafish, who have received that name for obvious stripe-related reasons. These particular zebrafish are residents of the National Institutes of Health, where they provide researchers with the means to study disease and understand more about how life develops. And here, thanks to the power of fluorescent proteins and microscopy, we see the zebrafish in a whole new palette, lit up in electric shades of blue and orange.

This image is first and foremost discovery, the result of a scientific hunt for a series of vessels inside the zebrafish whose existence might help scientists understand human diseases. But we’ll get to that in a bit. Because what we can also appreciate is that this image is stunning.

There’s the clarity and contrast of the colors, the sense of texture as the scales begin to overlap. You don’t have to understand everything going on in this image to find it beautiful…just like any art, really. Which is why it’s perhaps not surprising that in 2020, the scientist who took this picture submitted it to the Nikon Small World Photomicrography Competition and won.

The Nikon Small World Competition began in 1975 with the photomicrography contest, providing a showcase for all of the spectacular imagery that many masters of microscopes have observed and created, using whatever subject or technique that suits them. And in 2011, Nikon added a new video category called Small World in Motion. Every year, Nikon gathers a panel of judges to go through the submissions and decide on the winner.

And in 2021, that panel of judges included me, your trusty Journey to the Microcosmos host Hank Green. I was there, as you might imagine, not so much for my technical expertise as I was to get excited about and interested in the stories behind the images. And I said yes, not just for the free camera that I did get, but also to have a couple of days to sit around with true experts in their fields and to get some real behind the scenes insights into science that you can’t really get by reading articles, and I was not disappointed by the insights of my fellow judges, who are true experts and were really lovely people.

The 2021 winner of the Small World in Motion competition was this spectacular clip of symbiotic protists that live inside of a termite’s gut, taken and submitted by Fabian J. Weston from Australia. Filmed with polarized light and a microscope from the 1970s, you can see how much these organisms resemble organisms that you have seen in our episodes.

But these organisms have managed to carve out a home for themselves inside of termites, where they help their host digest wood and other plants. This is one of the transportive experiences of microscopy, the way that one image can reveal a world that is both so alien and unifying at once. And if there’s an animal that has embodied that dichotomy over and over again, it is the one we started this episode with: the zebrafish.

Now, on the one hand, it doesn’t seem like we should be finding a lot in common with a striped minnow. This is a fish that spawns eggs when daylight breaks; that has those eggs fertilized outside of its body; and that will produce hundreds of offspring through this method over the course of a week. And their embryos develop really quickly, assembling a head, tail, and heart within 24 hours of fertilization.

So when you hear all that—the daylight spawning, the external fertilization, the rapid development—you probably would not expect to find much common ground with the zebrafish. Except that we do share common ground—we share about 71% of our genome with a zebrafish, and many of those genes are valuable counterparts to understanding human diseases. This combination of similarities and differences make zebrafish an extraordinary resource for scientists.

As an embryo and larva, the zebrafish is transparent. And with the right combination of pigment mutations, scientists have been able to create a ghostly, translucent version of the fish called casper. That clarity makes it much easier for scientists to observe the inner workings of the fish under the microscope compared to, you know, much more opaque animals, like us or mice.

And since zebrafish are easy to take care of and regularly make embryos, they provide many, many opportunities for researchers to search for equivalents to our own selves in the fish. In the case of the image we just showed at the beginning of the episode, what researchers were pursuing was a series of lymphatic vessels inside the zebrafish’s skull. In mammals, these vessels maintain the right balance of fluids in our nervous system, making them potentially important in understanding diseases like Alzheimers.

And being able to use zebrafish to study these vessels would be amazing…except for one problem: no one had ever observed lymphatic vessels in the skull of non-mammals. No one, that is, until Daniel Castranova and his fellow scientists in Brant Weinstein’s lab at the NIH. They used fluorescent proteins in transgenic zebrafish to highlight the lymphatic vessels, bones, and scales.

And you can see those parts of the zebrafish here: the lymphatic vessels are shown in orange, the bones and scales are shown in blue. To take these images, the researchers anesthetized a juvenile zebrafish and mounted it on agarose to hold it still. Then they used a confocal microscope to divide and image the fish in layers.

It’s a bit like cutting the fish into cross-sections, only there’s no need to make a physical cut. The microscope creates those cross-sections through its own optical methods. The result is around 387 images that could then be stitched together to create one final image.

But this image is not just a 2-D photograph. It is a three-dimensional reconstruction, creating a map of cells inside the zebrafish that tells the researchers which vessels are inside and outside the skull. This map revealed that zebrafish have lymphatic vessels inside their skulls.

Moreover, researchers can easily do live imaging of these vessels. They can even see immune cells traveling through those vessels. What the final product reveals is not just something new, and not just something beautiful.

What this image reveals really is the possibility we continue to find in zebrafish. Much of this possibility is scientific, a future where experiments with zebrafish contribute to a greater understanding of disease. There is so much work that goes into making images like this one and all the other Nikon Small World submissions, so much careful thought and technique to determine how to use biology and technology at once.

And all of it hinges on the microscope, a scientific and artistic instrument rolled into one that has allowed its many masters to craft visions of worlds that contain bits of ourselves. Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you again to Nikon Healthcare for helping us make this video.

If you want to learn more about the imaging technology that helps to create amazing microscopy like what you saw in this video, make sure to check out the link in the description, and if you’d like to see more imagery and video that blends science and art, check out the microscopy galleries at I know I have spent a lot of time there. A big thanks to all of the people whose names are on the screen right now.

They are our patrons on Patreon. Patreon is a place where people support the things that they think should exist in the world. And all of these people have decided that they want Journey to the Microcosmos to exist in the world, and gosh darn it, if we don’t agree with them.

So, thank you all so much, we obviously could not do this without your support. If you would like to become one of these people, you can do that at If you want to see more from our Master of Microscopes James Weiss, you can check out Jam & Germs on Instagram, and if you want to see more from us, there’s always a subscribe button somewhere nearby.