Väkevä L, Mackie E, Kantomaa T, Thesleff I
Department of Pedodontics and Orthodontics, University of Helsinki, Finland.
Anat Rec. 1990 Sep;228(1):69-76. doi: 10.1002/ar.1092280111.
Tenascin is a glycoprotein of the extracellular matrix, which has been associated with differentiation of hard tissue forming cells. Alkaline phosphatase (AP) is involved in calcification, and it has also been suggested to function in cell differentiation. We have compared the distributions of tenascin and AP in the developing skull and teeth of embryonic and growing rats and mice. Tenascin was localized by immuno-Peroxidase and AP by enzyme histochemical staining of tissue sections. Both tenascin and AP were largely restricted to bone, cartilage, and teeth. In cartilage, tenascin was expressed in the perichondrium, whereas AP activity was detected only in the hypertrophic cartilage. In growing intramembranous bone, tenascin and AP were expressed in the periosteum and endosteum. AP activity was restricted to the inner layer of the periosteum, whereas tenascin expression extended to the more superficial layers. In bud-staged teeth tenascin but no AP activity was localized in the condensing mesenchymal cells around the epithelial bud. At the bell stage both tenascin and AP activity were localized in the cuspal mesenchyme, and the intensity of staining decreased towards the cervical region. In summary, tenascin was present at all sites of AP activity except in the epithelial cells of the enamel organ and the hypertrophic cartilage of the mandibular condyle. In mesenchymal tissues tenascin was more widely distributed than AP. It can be suggested that tenascin has functions at earlier stages of hard tissue formation than AP.
腱生蛋白是细胞外基质的一种糖蛋白，与硬组织形成细胞的分化有关。碱性磷酸酶（AP）参与钙化过程，也被认为在细胞分化中发挥作用。我们比较了腱生蛋白和AP在胚胎期和生长期大鼠及小鼠发育中的颅骨和牙齿中的分布情况。通过免疫过氧化物酶法定位腱生蛋白，通过对组织切片进行酶组织化学染色来定位AP。腱生蛋白和AP主要局限于骨骼、软骨和牙齿。在软骨中，腱生蛋白在软骨膜中表达，而AP活性仅在肥大软骨中检测到。在生长中的膜内成骨中，腱生蛋白和AP在骨膜和骨内膜中表达。AP活性局限于骨膜的内层，而腱生蛋白的表达延伸至更表层。在牙蕾期牙齿中，腱生蛋白定位于上皮芽周围的凝聚间充质细胞中，但未检测到AP活性。在钟状期，腱生蛋白和AP活性均定位于牙尖间充质中，且染色强度向颈部区域降低。总之，除了釉质器官的上皮细胞和下颌髁突的肥大软骨外，腱生蛋白存在于AP活性的所有部位。在间充质组织中，腱生蛋白的分布比AP更广泛。可以推测，腱生蛋白在硬组织形成的早期阶段比AP发挥着更重要的作用。
