In this little blog, so far, I exposed the enemy – the animals that don’t let me to do my work. I will say now what my work is. Here is the topological model of a structure that I first described in 1980 as the idealised structure of intestinal crypt.
Here, there are cells in a fast proliferating tissue forming a finger-like structure. These cells divide in waves going around the structure in the spiral rows, here – the green cells resulted from such wave of cell division. The consecutive waves of cell division result in the growth of the structure. The secret of this order of division is in the preservation of the shape of the structure and its diameter, i. e. the obligatory requirement for the tissues in the adult organism that can renew their cells without affecting the shape of the tissue (i. e. dividing in the steady state). In the real intestinal crypt, the excess of cells at the open end is being passed to the villus and then shed to the intestine. This was the first model that showed the actual cells, their division and fate.
The model is obviously 3-dimensional. However, it was made with the rules operating only in two dimensions. It is a flat surface that was bending when the bottom was forming. Here, I start thinking that Nature can make complex structures without ever being bothered about the third dimension. Of course, the elements, the building blocks supply that third dimension in the various physical objects.
Recently, I asked myself whether other tissues can also represent the 2-dimensional design. While the crypt is a part of one-cell thick layer of epithelium, in other tissues cells are seen “packed” in 3-dimensions. Yet, I am coming to the stunning conclusion that this is an illusion, and that even liver originates from a 2-dimensional design. Here is what I mean:
Above, the 2-dimensional model of nodal growth in embryogenesis of liver. Now, in this growth the nodes come together and cells eventually fill the space between them. You have what appears as a dense 3-dimensional tissue, but in fact, the structure came from a 2-dimensional design. If this is indeed so, that is also the structure of many other tissues that arise as nodes and appear as nodes in the adult organism also.
(to be continued)