Peacekat, this is a very long video and is worth it for any who has not seen it (sure it was posted before). It goes into great detail about epithelial breast cells and CCR5 around the 20 min mark and general leron info at min 29. He has some cartoon like drawings that are humorous for those with an actual sense of humor.

He corrects his misguided pricing issues at the end

https://www.youtube.com/watch?v=0yN7llL9xNA