Shape
There exist cells which have a variable shape, such as the leukocytes, and some connective tissue cells and cells with a stable shape, such as the erythrocytes, epithelial cells, muscle cells and nerve cells. These stable cells always have a typical more or less fixed shape which is a specific characteristic of each cell type. Some cells are encased in a rigid wall, which constrains their shape, while others have a flexible cell membrane (and no rigid cell wall).
The shape of the cell depends partly on the surface tension and viscosity of the cytoplasm, the mechanical action which the adjoining cells exert, the rigidity of the membrane and the functional adaptation.
Many cells when isolated in a liquid medium tend to take a spherical form, obeying the laws of surface tension. This is the case with the leukocyte which in the circulating blood are spherical, but by the influence of adequate stimuli can emit pseudopodia (ameboid movement) and become completely irregular in shape.
The cells of many plant and animal tissues have a polyhedral shape, statistically more or less constant, determined principally by pressure from adjacent cells.
The shape of the cell depends partly on the surface tension and viscosity of the cytoplasm, the mechanical action which the adjoining cells exert, the rigidity of the membrane and the functional adaptation.
Many cells when isolated in a liquid medium tend to take a spherical form, obeying the laws of surface tension. This is the case with the leukocyte which in the circulating blood are spherical, but by the influence of adequate stimuli can emit pseudopodia (ameboid movement) and become completely irregular in shape.
The cells of many plant and animal tissues have a polyhedral shape, statistically more or less constant, determined principally by pressure from adjacent cells.
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