Final answer:
The longitudinal layer consists of cells in organs and tissues that stretch, such as the skin, heart, and muscles. These cells contract to cause the tissues to stretch or contract along their length.
Step-by-step explanation:
The longitudinal layer is a layer of cells in organs and tissues, such as the skin, heart, and muscles, that stretch. These cells are responsible for maintaining the sheet-like formation of tissues. When the cells in the longitudinal layer contract, they cause the tissues to stretch or contract along their length.