Unlocking the Secrets of Maps: Exploring the Human Cell Atlas

The Human Brain Cell Atlas v1.0, photo courtesy of Human Cell Atlas DATA PORTAL, cells colored according to tissue type

Skeletons used to perch on the counters in my old Human Body Systems class, and over the year, they slowly came to life, gaining clay muscles every few class periods. When the whole human skeleton had been mapped out, it was monumental. Now, scientists are embarking on mapping all the cells (specifically, tissues, or, group of the same cells) in the human body.

Dubbed the name, The Human Cell Atlas, the project aims to make a 3 dimensional atlas of the entire body and is a global undertaking. However, the plan is well underway and currently,18 major organs and tissues are being mapped (for instance, the lung, the nervous system, and eye). With the use of this atlas, scientists believe that insight on diseases such as cancer, liver disease, and lung disease will be provided.

The single cell atlas of the human retina (make sure to open this up and see, it's so fascinating) is especially interesting. The human retina is composed of five types of neurons. To capture all the cell types, scientists created a single cell atlas containing 3.4 million single cells from 122 donors. Over 120 cell types are distinguished (the five types of neurons have many, many subcategories).

To take advantage of the cell atlas, press the teardrop buttons on the left column (cell type and tissue is most interesting!). There is a toggle option for each category, for instance, if you press the toggle button for cell type, a large list of cell types pops up, with its respective color shown next to it. If you hover your mouse over a specific cell type, the color on the atlas become more pronounced.

It's fascinating to see which cells are common or uncommon, with the cell type retinal pigment epithelial cell showing up only 863 times, compared to the hundreds of thousands of other cells. Next, I recommend that you close the list of cell types and open up the tissue drop down box. If you keep the cell type coloring on, you're able to see the proportion of cell types that make up the four overarching cell categories. Although doing a deep dive on ALL the cell types is difficult, it can be noted that the peripheral region of retina has many retinal rod cells, which work to detect light in dim environments.

Another cell atlas, the Human Retina Cell Atlas, is much more easy to swallow, with it's friendly introduction to the site's inner workings and friendly navigation. To the right, where it is titled Legend, is the proportion of cell types in the human retina. Notably, the majority of cells are rods, which are appropriate since rods not only help humans see in low light, but provide peripheral vision.

Some other notable cell atlases are the Human Brain Cell Atlas and the Human Lung Cell Atlas.