The way organisms develop from the initial single-cellular state to a complex final assembly like the human body, and how the final body is maintained throughout life, is one of the greatest... Show moreThe way organisms develop from the initial single-cellular state to a complex final assembly like the human body, and how the final body is maintained throughout life, is one of the greatest mysteries and it’s understanding one of the biggest scientific challenges. Lately, it came as a surprise that the initial assembly and the later maintenance of integrity is not only determined by intricate biochemical communication networks, but in part by physical forces that cells, their neighbors, and their environment apply in a bidirectional manner. The resulting collectivity of cell behavior determines the development of organisms, and are crucial to the health and disease state of the organism.In this thesis, we developed and utilized concepts from physics to quantitatively understand forces that develop between cells and their environment, and towards neighboring cells, and how the interplay between these forces regulates the arrangement, shape, and topology of tissue. The topics range from the development of novel experimental methods to the combination of experimental observations with theoretical descriptions. Our results contribute to a better understanding of cell and tissue integrity. Show less