title: Skeletal biology in the toothless (osteopetrotic) rat.
abstract: The toothless (tl) rat is a nonlethal osteopetrotic mutation characterized by the presence of few osteoclasts and the failure to be cured by bone-marrow transplantation. We examined the skeletal biology of tl rats and normal littermates up to 6 weeks after birth. Osteoclasts in tl rats were small, reduced 25-fold in number, and had greatly reduced concentrations of acid hydrolases. Bone shape internally and externally reflected reduced bone resorption, and tl rats were hypophosphatemic and mildly hypocalcemic at 2 weeks. These data indicate that the basic defect in tl rats is one of differentiation of osteoclasts and, coupled with the observation that normal bone-marrow cells cannot develop into osteoclasts in the tl skeleton, suggest that the defect lies in the skeletal micro-environment.
authors.affiliation: Department of Anatomy, University of South Dakota School of Medicine, Vermillion 57069.
authors.forename: M F
authors.initials: MF
authors.lastname: Seifert
authors.forename: S N
authors.initials: SN
authors.lastname: Popoff
authors.forename: S C
authors.initials: SC
authors.lastname: Marks
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology*; D008854:Microscopy, Electron; D010010:Osteoclasts / Q000473:pathology; D010022:Osteopetrosis / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D051381:Rats; D011922:Rats, Mutant Strains; D014070:Tooth / Q000000981:diagnostic imaging / Q000473:pathology