Pancreatic cells, which secrete a large amount of digestive enzymes, are labeled with radioactive leucine and then chased for several hours with nonradioactive leucine. photographic emulsions are prepared at different times during the chase. where would the black spots appear on an emulsion prepared 3 hours after the pulse? view available hint(s) pancreatic cells, which secrete a large amount of digestive enzymes, are labeled with radioactive leucine and then chased for several hours with nonradioactive leucine. photographic emulsions are prepared at different times during the chase. where would the black spots appear on an emulsion prepared 3 hours after the pulse? rough er golgi apparatus secretory vesicles exterior of the cell