Histocompatible cells for the resolution of osteopetrosis in microphthalmic mice

Harwell microphthalmic mice from a small closed line-bred colony, when separated after 2 weeks parabiosis with normal siblings, showed later resolution of their osteopetrosis (except for jaws and tail). The former parabionts were tolerant of each other’s skin. This mutual tolerance was shown by skin grafts to be due to reduced heterozygosity of the stock, not to parabiosis. Such tolerance would allow acceptance by the osteopetrotic mice of precursors of normal bone resorbing cells from the sibling’s blood. Despite skeletal improvement the affected mice remained unthrifty.