Chapter 8
Morphogenesis
In this book, morphogenesis is defined as a change in shape. Like plastic deformation, a morphogenetic shape change is permanent in the sense that it remains
relatively intact when all external loads and constraints are removed. Removing
these outside factors eliminates elastic deformation, leaving behind the shape caused
by morphogenetic processes.
Since growth involves similar behavior, it should not be surprising that growth
often plays a major role in morphogenesis. In fact, the growth theory discussed
in Chap. 6 can be used to simulate most morphogenetic processes, even those
that do not involve volume changes, e.g., active contraction. As discussed earlier,
contraction can be simulated using a variation of RHM growth theory.
The creation of biological form involves a combination of genetics, biochemistry,
and mechanics. Genes provide instructions for the cells to follow, and biochemical
signals (morphogens) help distribute these instructions at appropriate times to
appropriate places for implementation. However, physical forces generated by the
cells do the heavy lifting involved in constructing an embryo. Embryonic cells
have a relatively limited number of morphogenetic tools in their toolbox, including
proliferation, hypertrophy, crawling, and active shape change. However, there is
an essentially unlimited number of ways these tools can be combined to build
an embryo. The book by Davies (2005) provides an outstanding introduction to
morphogenesis from a biophysical perspective.
Morphogenesis is fundamentally a tissue-level process. Global shape of an
organism and its composite structures are of utmost importance. The embryo does
not care how these shapes are created, as long as they function normally in the
end. To minimize abnormalities, nature has devised multiple mechanisms to create
essentially the same shape. Some of these mechanisms likely function as backups,
in case something goes awry. Moreover, like integrating noisy data, minor variations
at the cell level may have negligible effects on macroscopic morphology.
For researchers, this emphasis on global form has both advantages and disadvantages. On the plus side, continuum models are appropriate for simulating tissue-level
© Springer Nature Switzerland AG 2020
L. A. Taber, Continuum Modeling in Mechanobiology,
https://doi.org/10.1007/978-3-030-43209-6_8
401
Morphogenesis
In this book, morphogenesis is defined as a change in shape. Like plastic deformation, a morphogenetic shape change is permanent in the sense that it remains
relatively intact when all external loads and constraints are removed. Removing
these outside factors eliminates elastic deformation, leaving behind the shape caused
by morphogenetic processes.
Since growth involves similar behavior, it should not be surprising that growth
often plays a major role in morphogenesis. In fact, the growth theory discussed
in Chap. 6 can be used to simulate most morphogenetic processes, even those
that do not involve volume changes, e.g., active contraction. As discussed earlier,
contraction can be simulated using a variation of RHM growth theory.
The creation of biological form involves a combination of genetics, biochemistry,
and mechanics. Genes provide instructions for the cells to follow, and biochemical
signals (morphogens) help distribute these instructions at appropriate times to
appropriate places for implementation. However, physical forces generated by the
cells do the heavy lifting involved in constructing an embryo. Embryonic cells
have a relatively limited number of morphogenetic tools in their toolbox, including
proliferation, hypertrophy, crawling, and active shape change. However, there is
an essentially unlimited number of ways these tools can be combined to build
an embryo. The book by Davies (2005) provides an outstanding introduction to
morphogenesis from a biophysical perspective.
Morphogenesis is fundamentally a tissue-level process. Global shape of an
organism and its composite structures are of utmost importance. The embryo does
not care how these shapes are created, as long as they function normally in the
end. To minimize abnormalities, nature has devised multiple mechanisms to create
essentially the same shape. Some of these mechanisms likely function as backups,
in case something goes awry. Moreover, like integrating noisy data, minor variations
at the cell level may have negligible effects on macroscopic morphology.
For researchers, this emphasis on global form has both advantages and disadvantages. On the plus side, continuum models are appropriate for simulating tissue-level
© Springer Nature Switzerland AG 2020
L. A. Taber, Continuum Modeling in Mechanobiology,
https://doi.org/10.1007/978-3-030-43209-6_8
401