A Stroll Through the Cells of the Retina

What am I looking at?

This video shows the cells that make up a section of the retina of a zebrafish larva only about a day after fertilization. Several cellular components are labeled: the plasma membrane is blue, the Golgi apparatus is green, the endoplasmic reticulum (ER) is purple/pink, and the mitochondria are orange. The video starts by showing the entire section of retinal tissue that was imaged. Then the plasma membrane label is removed to highlight the internal cellular organelles. Then the section of tissue expands to show each of the individual cells within, outlined by their translucent blue plasma membranes and showing the Golgi, ER, and mitochondria within each cell. During this part of the video the blue plasma membrane label is removed once again to show the internal organelles more clearly. The video ends by zooming out to show the whole tissue section once more.

Biology in the Background

Zebrafish eyes are similar to ours. We share all the major structures, such as a single lens to focus light, a retina with photoreceptor cells to detect light, and a liquid-filled cavity between the two known as the vitreous cavity. During development, the cells of the eye and the organelles within them undergo significant changes to create a fully functional adult eye.

Videos like this one can provide researchers with unique insights into the organization of the developing cells and their organelles at a specific developmental stage. Here we can see that in different parts of the tissue sample, the internal organelles within cells are organized differently. For example, cells from the middle of the sample show more ER (more purple/pink) while cells on the top right side of the sample show more mitochondria (more orange). This is because different layers of the sample will become different cell types in the adult retina.  

While these insights cannot be applied directly to the development of a human eye, they still provide scientists with foundational knowledge regarding the developmental process and its timing– information that can be used to set the stage for vision research in other vertebrates, including humans.

These cells vary in size, but those in the middle of the sample are about 15 micrometers long, or roughly five times smaller than the width of a human hair.

Technique

This video was created using confocal microscopy.