Fibroblasts: They are large, flat, highly branched. They secrete and maintain fibres.
Plasma cells: They are oval in shape and have small nucleus. They produce antibodies.
Macrophages: They are amoeboid in shape. They defend against micro-organisms. They
ingest the micro-organisms.
Mast cells: They are large cells having a spherical nucleus with granular cytoplasm. They
are associated with secretion of substances like serotonin, heparin and histamine.