Written Assignment Due Monday Oct 16, 2017

Unsolved Questions About: "Connective Tissue Development"
Chapter 10 in Cell and Matrix Mechanics edited by Kaunas & Zemel
In relation to Chapter 11 by Larry Taber (and maybe also Chapter 12)

A) In Figure 10.6 a thin sheet of rubber is being compressed at the bottom and stretched at the top. Please describe and/or sketch what the arrangement of rubber sheet and tissue culture cells would have looked like if we had a thin section perpendicular to the plane of focus in this photograph.

B) In figures 10.4, 10.5, 10.7 10.8 and 10.9 collagen gels are being compressed where? And are being stretched where? (Your answers can be either descriptions or sketches, or some combination (& I know you can't sketch an e-mail)

C) Figure out what figures 10.4 and 10.5 would have looked like if polarized light microscopy had been used.

D) Figure 10.3, is a (somewhat too dark! Sorry) polarized microscopy view of a thin section through where a cartilage (upper right) is being replaced by formation of bone (lower left). Surprisingly, the yellow and blue colors indicate that the directional orientation of collagen fibers is changing by ninety degrees where bone is forming.

Please either suggest an explanation for this right-angle change in direction, or propose some other way of explaining why the photograph looks as if such a 90 degree rotation is occurring. Alternatively, propose some other explanation or interpretation of this photograph.

E) Near the end of the top paragraph on page 247, I made a gently sarcastic joke in response to the criticisms made by the German researcher Eckes and her ten coauthors about the theory proposed by David Stopak and me.

What was the theory we proposed? What experiment did Eckes et al. do to test this theory? What was the result? How did their results differ from what we would have predicted? And what was meant to be funny about my joke?

F) Find some specific phenomenon or illustration in Larry Taber's paper (Chapter 11) that could have been extended, improved, or contradicted by any of the special methods used in my chapter (Chapter 10)

G) Which of these physical forces listed below are discussed in both the Harris and the Taber chapters?

    Just in the Taber paper?
    Just in the Harris paper?
    Discussed in neither the Harris nor the Taber Paper?
    But (optional) discussed by some other chapter in that book? On what page or pages?

    1) Acto-myosin contraction
    2) Pressure of fluids
    3) Osmotic pressure
    4) Electroosmosis
    5) Cell-cell adhesion forces
    6) Elastic stretching of collagen
    7) Donnan Equilibrium
    8) Malcolm Steinberg's Thermodynamic theory
    9) Cell growth, in the sense of cell enlargement
    10) Mitotic cell divisions