Can leydig cells survive infection over other cells in testicle if the testicle atrophies from being treated late? supposedly they can resist chemo?

More often germ cells: but both cell also possible. Certain infections like mumps will cause testicular atrophy , as the germ cells that produce sperm are more proliferative ( active division ) than Leydig cells . In men with fertility problems due to atopy it is the sperm count that will be low , but testosterone levels could be normal , Leydig cells are spared. Some times may need testicular biopsy .

Store cells b4 chemo: chemotherapy is a cellular poison, so it is a good idea to store away as many progenitor cells, including sperm, in case the chemo kills a large volume of healthy cells that can't be replaced.