But in PPS patients, all the skeletal muscles may be expecially weakened to start off with, so further weakening the diaphragm in these patients can seriously affect breathing. C. an autoimmune disease 6. To increase the thoracic volume, it's necessary to contract the diaphragm, which pulls it down into the abdominal cavity. If the abdominal cavity has more stuff in it than usual, it'll be harder to move the diaphragm downwards into it. The clonal descendants of a single cell .
Cleavage involves subdivision of a huge cell into smaller and smaller cells.
It does not involve growth in size. Total volume of embryo stays about the same, so amount of dye per unit volume doesn't change. B. Cells move extensively between the blastula and gastrula stages. In other words, the fate of cells at the 8 cell stage is not yet set but the normal fate of cells in the gastrula is set. The only way to find out if cells are truly determined is to transplant the cells and see what happens to them.