No abstract

The sensitive and high resolution method of in situ hybridization technique has been developed using digoxigenin-11 UTP labeled cRNA as a probe. The system was applied to the decalcified mineralized tissues such as bone and dentin. Using the system, the localization of the mRNA of bone extracellular matrix proteins, osteopontin (Osp), osteonectin (Osn), Osteocalcin (Osc) and matrix Gla protein (MGP) was examined in decalcified bone. Decalcified femurs and mandibulae of embryo, neonatal, 2 to 40-week old mice were used for examination.Osn and Osc mRNAs were localized at osteoblast in bone and at odontoblast in dentin. Although the distribution pattern of Osn positive cells and Osc positive cells was partially overlapped, Osc mRNA was detected at matured osteoblast and odontoblast but Osn mRNA was detected not only at matured but differentiating osteoblast such as flat osteoblast in the periosteal layer. Osp mRNA was detected at osteoblast in bone, but no apparent expression of Osp mRNA was found at odontoblast in dentin. MGP mRNA was detected in hypertrophic chondrocytes.These results indicated the usefulness of this system for identifying the cell types in bone and dentin.

The expression of the mRNAs for osteonectin (ON), osteopontin (OPN), osteocalcin (OC), and matrix Gla protein (MGP) was studied by in situ hybridization during the healing process of an experimental fracture in adult rat femora. At day 1 postoperatively, ON mRNA was detected in the proliferating periosteum. At day 3, ON, OPN, and OC mRNAs were detected in woven bone. From day 5, MGP and ON mRNAs were detected in the immature chondrocytes. From day 7, ON, OPN, and OC mRNAs were detected in the osteoblastic cells in newly formed endosteal trabecular bone. OPN mRNA was also detected in some of the osteocytes in trabecular bone. From day 14, OPN and MGP mRNAs were detected in newly formed periosteal hypertrophic chondrocytes, and the ON, OPN, and OC mRNAs were detected in osteoblastic cells in newly formed periosteal trabecular bone. Although the cell types that expressed each mRNA in fractured bones were similar to those in embryonic bones, the time course of these mRNA expression in fractured bones was different from that in embryonic bones. We considered that this system is useful to investigate the phenotypic change in osteogenic and chondrogenic lineage cells that appears during fracture healing at the molecular level.

Porencephaly was observed in a female cynomolgus monkey ( Macaca fascicularis ) aged 5 years and 7 months. The cerebral hemisphere exhibited diffuse brownish excavation with partial defects of the full thickness of the hemispheric wall, and it constituted open channels between the lateral ventricular system and arachnoid space. In addition, the bilateral occipital lobe was slightly atrophied. Histopathologically, fibrous gliosis was spread out around the excavation area and its periphery. In the roof tissue over the cavity, small round cells were arranged in the laminae. They seemed to be neural or glial precursor cells because they were positive for Musashi 1 and negative for NeuN and GFAP. In the area of fibrous gliosis, hemosiderin or lipofuscin were deposited in the macrophages, and activated astroglias were observed extensively around the excavation area.