Pancreas Histology Practice Name this group of cells (the lighter group) 1 Name this group of cells (the darker group) 2 Pancreatic islet immunostained dark for insulin Pancreatic islet immunostained dark for glucagon 23 4- Identify the pancreatic islet, exocrine cells, Alpha cells and Beta cells in the slides on the left. 1. What triggers Beta cell activity and what do Beta cells produce? 2. What triggers alpha cell activity and what do alpha cells produce? video on pancreas function