What is the mechanism of paracrine signaling?

In paracrine signaling, cells are able to communicate with one another by secreting signaling molecules. These signaling molecules bind to neighboring cells and activate them. This type of signaling does not occur in long distances throughout the circulatory system. Instead, cells communicate via the secretion of chemical messengers, which are ligands that diffuse through space between the cells. The distance that the molecules travel determine the quantity of surrounding cells each cell can interact with to facilitate their responses. Once the signaling molecules are transmitted to target cells, they go through some type of alteration or effect to activate a pathway. This then leads to a cellular response, such as responses to allergens or formation of scar tissue depending on the pathway being activated. It is important to note that this type of signaling does not require any contact as it relies on diffusion of nearby signaling molecules.