The grey lethal mouse is an osteopetrotic mutant which cannot be identified by its external appearance (grey fur) until eight days of age and dies within one month of birth. Techniques for the identification of neonatal mutants would greatly facilitate study of the pathogenesis of osteopetrosis and its early treatment. Under hypothermal anesthesia, the left lower limbs of neonatal mice were amputated just above the knee joint. The external appearance of two day old amputated tibiae could be correlated with the external appearance of the mice at eight days of age. The diaphyses of normal tibiae appeared red under the dissecting microscope due to the presence of hemopoietic tissue occupying the central marrow cavity. Grey lethal tibiae appeared opaque because relatively more unresorbed bone occupied the center of the diaphysis. Histologic examination showed that in normal mice at birth, the mandibular incisor extended posteriorly to the molar region of the jaw, but that in grey lethals dense bone prevented the incisor from growing posteriorly in this fashion.
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)