Re: Histamine
Receptors don't release anything! they respond to chemical messengers.
Laura, you need to use google a bit more. The simple phrase "Which cells release histamine and other chemical messengers?" put into google gave a huge number of hits.
Top of the list was this:
histamine (biochemistry) -- Britannica Online Encyclopedia
your answer is there if you read the entry.
Please, please please use the skills you already possess before using us as your own research team. We don't mind the odd question, but we don't like having to do all the work for you!
“It's not worth doing something unless you were doing something that someone, somewhere, would much rather you weren't doing.”
Terry Pratchett