GO:0042827

Electron-dense granule occurring in blood platelets that stores and secretes adenosine nucleotides and serotonin. They contain a highly condensed core consisting of serotonin, histamine, calcium, magnesium, ATP, ADP, pyrophosphate and membrane lysosomal proteins. [GOC:jl, http://www.mercksource.com/, PMID:10403682, PMID:11487378]