I was taught in biology class in the 9th or 10 grade that red corpusles are made in the bone marrow ... I now know I don't have to trust that as a fact. I was taught alot of untrue things in school.
I've read recently that the villi in the small intestines pick up liquids that ARE our blood ... that our blood plasma is the same chemicals as chloraphyll in a plant minus the red corpusles ... didn't say in that article where the red blood cells actually come from.