This is basically a fun question, inspired by this answer on scifi.se. So, which cell type will have the greatest number of mitochondria? Obviously, I am talking about wild type, healthy individuals and am looking for a rule of thumb. I realize that the number can change under different conditions/ between different individuals.
Off the top of my head, I would say that it's sperm cells given the strenuous exercise they need to perform and their MT-packed axonemes but perhaps there are better contenders?
I am primarily interested in human cell types but answers dealing with other mammals are welcome.