| This is a study of cell and developmental biology based on the principles of mechanics. Cells and embryos are idealized as axisymmetric shell-like bodies containing a body of incompressible material. According to this view, this study devotes its first part to developing computational tools based on the finite element method. The tools formulated include an axisymmetric shell/membrane element based on a stress resultant formulation, valid for modeling finite bending, shearing and stretching; a volume constraint algorithm based on the Lagrange multiplier method; and a contact algorithm based on the penalty method. These analysis tools facilitate the study of three commonly used mechanical experiments on sea urchin eggs--the compression experiment, the suction experiment, and the magnetic particle experiment. These numerical simulations are useful not only in obtaining mechanical property data, but in providing insights to these mechanical experiments that other approximate analyses cannot provide. The analysis tools are also utilized to study two developmental events--gastrulation in sea urchins and neurulation in amphibia. By not focusing on the molecular basis of the cell shape changes during development, but concentrating on the mechanical consequences of the motion itself, this study reveals a great deal about the mechanisms driving embryonic shape changes. |
