sentences:  MK-4 is produced via conversion of vitamin K1 in the body, in the testes, pancreas and arterial walls.While major questions still surround the biochemical pathway for the transformation of vitamin K1 to MK-4, studies demonstrate the conversion is not dependent on gut bacteria, occurring in germ-free rats and in parenterally-administered K1 in rats.In fact, tissues that accumulate high amounts of MK-4 have a remarkable capacity to convert up to 90% of the available K1 into MK-4.