My paper recently written and published in honor of the great Russian embryologist Lev Beloussov, who died in fall 2017.
link to this paper online
Please read this paper, and think especially about the following questions:

How can physical properties of cells cause their geometric shapes?

Using homeostasis to try to explain tube formation.

If being cylindrical is sufficient to cause strengths of circumferential tension to exert twice the force of longitudinal tensions, then is the reverse also true?

Is having a two to one ratio of directional tension enough to cause surfaces to become cylinders? (Just as having surface tensions be equally strong in all directions causes materials to round up into spheres.)