Nakamura H, Kimura S, Kenmotsu S, Sakai H, Saku T, Ozawa H
Department of Oral Anatomy, Niigata University School of Dentistry, Japan.
Arch Histol Cytol. 1995 Aug;58(3):323-34. doi: 10.1679/aohc.58.323.
We studied the immunohistochemical localization of CD44 and heparan sulfate (HS) chains in rat enamel organ by confocal laser scanning microscopy and transmission electron microscopy. We also investigated the binding sites of basic fibroblast growth factor (bFGF), one of the heparin-binding growth factors (HBGF), on Microslicer-sections to clarify its role in the cell-cell interaction of HS. At the differentiation stage of ameloblast, weak immunoreactivity for CD44 was detected on the plasma membrane of the inner enamel epithelium, external enamel epithelium and the cells adjacent to the inner enamel epithelium. In accordance with the differentiation of preameloblasts into secretory ameloblasts, this immunoreactivity increased in stratum intermedium cells. At the secretory stage, stratum intermedium cells showed the most intense immunoreactivity in the enamel organ. At the maturation stage, strong immunoreactivity was seen on papillary layer cells. On the other hand, the lateral plasma membrane of ruffle-ended (RA) and smooth-ended ameloblast (SA) showed weak reactivity. No immunoreactivity was detected on the ruffled border of RA and the distal plasma membrane of SA. Immunolocalization of HS chains was similar to that of CD44. The binding activity of bFGF was also intense on stratum intermedium cells and papillary layer cells. These findings suggest that: 1) stratum intermedium cells and papillary layer cells express CD44 and HS chains in accordance with their differentiation; 2) HS chains on the plasma membrane of these cells may regulate calcium transport by their negative charge; and 3) HS chains on the stratum intermedium and papillary layer may play an important role in the differentiation and activity of ameloblasts by preserving HBGF.
我们通过共聚焦激光扫描显微镜和透射电子显微镜研究了大鼠牙釉质器官中CD44和硫酸乙酰肝素（HS）链的免疫组织化学定位。我们还研究了肝素结合生长因子（HBGF）之一的碱性成纤维细胞生长因子（bFGF）在微切片上的结合位点，以阐明其在HS细胞间相互作用中的作用。在成釉细胞分化阶段，在内釉上皮、外釉上皮以及与内釉上皮相邻的细胞的质膜上检测到CD44的弱免疫反应性。随着前成釉细胞分化为分泌性成釉细胞，这种免疫反应性在中间层细胞中增加。在分泌阶段，中间层细胞在牙釉质器官中显示出最强的免疫反应性。在成熟阶段，乳头层细胞上可见强免疫反应性。另一方面，皱褶末端（RA）和平滑末端成釉细胞（SA）的侧质膜显示出弱反应性。在RA的皱褶边缘和SA的远端质膜上未检测到免疫反应性。HS链的免疫定位与CD44相似。bFGF的结合活性在中间层细胞和乳头层细胞上也很强。这些发现表明：1）中间层细胞和乳头层细胞根据其分化表达CD44和HS链；2）这些细胞质膜上的HS链可能通过其负电荷调节钙转运；3）中间层和乳头层上的HS链可能通过保留HBGF在成釉细胞的分化和活性中发挥重要作用。
