Corpus spongiosum
There are man different reasons that you could be experiencing this. A "UTI" is the most common reason, which is a Urinary Tract Infection. Usually with these there is not any blood on the tissue....
Blood is a tissue, it is a connective tissue. Weird, I know but true.
bone marrow
Red bone marrow
Menstrual Blood Cells Contribution to Medicine
Development of Red Blood Cells to Embryonic Stem Cells
'Gut Flora' Separates Humans into Three Different Groups
How a Sports Massage Can Improve Your Training