Figure 7.

Accommodations must be made again. Animals have evolved mechanisms that maintain tissue size in the face of changing ploidy. These images from Fankhauser illustrate this point. Kidney tubules of the same size are constructed by larger and larger cells as ploidy increases, and cells must change their shapes so that the tubule diameter can remain constant. In the haploid animal, many nuclei can be observed around the tubule circumference, and so these cells have a columnar morphology. In the pentaploid animals, only one or two nuclei can be observed, and these much larger cells are flattened and squamous in order to enclose the same tubule diameter.