Cellular structures

When it comes to modeling cellular structures, I have to start talking about some of the features of the program I am using to do so. I am using the ray-tracing program Pov-Ray, which only allows to use geometric structures (including some derivations and combinations) for modeling. So, it is not possible to just sculpt a certain shape as in many other programs. There is a workaround, as it is possible to generate bodies from the gradual addition/subtraction of spheres (and cylinders). I don’t want to go into the theory, therefore I use a simple example to show, how it works: Imagine three identical spheres of different color.

In this example the yellow and green sphere are fused together, while the blue sphere is subtracted. The object generated by this procedure is called a blob in Pov-Ray.

Now I will use such blobs to model cellular structures. I first restrict myself to two dimensions for better clarity. First we need the positions of the later cells. Since I want to model somewhat elongated cells, these positions are distributed unevenly.

Now the sphere are replaced by blobs generated from a central sphere from which spheres at the positions of the surrounding cells are subtracted. This nicely represents the counterplay of the osmotic pressure of a given cell and the pressure from its surrounding cells in many tissues. As you may see below, by using a similar principal as in nature, we will come to similar results. (That’s what making a model is all about…). Well, for the time being the results do not look that much convincing, but that is only because I chose parameters demonstrating the formation of the blobs. In addition, the blobs are sectioned to have a better view.

Modelling cells

With the following parameters (increasing the pressure from the adjacent cells), the cells become more distinguishable.

Finally, I add some variation regarding the position of the individual cells …

… and increase the “pressure” in all structures.

So far everything was 2D; now let us switch to 3D (which is quite a demanding task at least for my computer…)

And here is the same structure with empty cells. My solution is not ideal, because, as soon as I try to make thinner cell walls, it becomes increasingly difficult to avoid holes within the walls.

Simple cells