Abstract
The first lecture gave a very general introduction to tissue physics, describing the classical approaches used by physicists to describe tissues, and introducing the tissues that serve as models for these lectures. The general approach of the lecture is to consider the cell as an elementary brick from which the tissue is built. There are then two possible approaches : a microscopic approach in which we start from the cell and build the properties of the tissue from those of the cell, and a macroscopic approach which characterizes the tissue by a few macroscopic parameters.
The best introduction to tissue physics is certainly D'Arcy Thompson's fine book on morphogenesis. In it, D'Arcy Thompson discusses tissue shapes by analogy with other known physical problems, such as soap bubbles, or by using mathematical constructs. Many of these ideas are now used in a more quantitative way by soft matter physicists to describe tissues.
An important feature is that tissue properties must be regulated to fulfill their biological function. There is, for example, regulation of tissue size, heterogeneity or cell differentiation. Two types of regulation are particularly important : chemical regulation via morphogens and mechanical regulation. The classic model for chemical regulation is that of Turing instability. Mechanical regulation is due to a coupling between tissue growth parameters and local mechanical constraints.
