So that is shown by these red dots. So let's begin with the mass cells. So mass cells on their surface contain these receptors and these receptors can bind antigens nonspecifically. And what that basically means is it doesn't matter what type of antigen is found in close proximity these mass cells will bind any antigen and once they bind that antigen they know that there is some type of pathogen in close proximity. And so what they begin to do is they remain within the tissue and they begin releasing chemicals. So what types of chemicals?