SPONTANEOUS MYELOFIBROSIS IN CASTRATED AND OVARIECTOMIZED NMRI MICE

The histopathological appearance of myelofibrosis of the bone marrow i s described in aged castrated males, ovariectomized females and in mal e and female control NMRI mice. The highest incidence of the lesion wa s observed in ovariectomized and female control mice where more than 9 0 % of the animals were affected. The presence of myelofibrosis in the bone marrow of ovariectomized females and castrated males indicates t hat estrogens may not play a major role in the development of the lesi on and other hormonal disturbances must also be considered.