Select all the criteria used to classify tissues into four major types.

Tissues are classified into four major types based on the following criteria:

1. Structure of Cells: The shape and size of the cells in a tissue vary based on their function. For example, epithelial cells are tightly packed to form a protective barrier, while muscle cells are elongated and contain fibers that help in contraction and relaxation.

2. Function: The function of the tissue also plays a crucial role in its classification. For example, nervous tissue is involved in transmitting signals, muscle tissue helps in movement, connective tissue connects and supports other tissues, and epithelial tissue forms the lining of body organs and surfaces.

3. Cell Composition: The type and number of cells in a tissue also determine its classification. For example, connective tissue consists of a variety of cells like fibroblasts, macrophages, and adipocytes.

4. Extracellular Matrix: The presence and type of extracellular matrix also help in classifying tissues. For example, connective tissues have an abundant extracellular matrix, while it is minimal in epithelial tissues.

5. Degree of Vascularity: Tissues are also classified based on their blood supply. For example, epithelial tissue is avascular (does not have blood vessels), while connective tissue is highly vascularized.

So, the major types of tissues - epithelial, connective, muscle, and nervous tissues - are classified based on these criteria.