White F H, Gohari K
J Cell Sci. 1984 Mar;66:411-29. doi: 10.1242/jcs.66.1.411.
Desmosomes in stratified squamous epithelia appear to exhibit quantitative alterations during differentiation. In this work we use stereological and other morphometric methods to quantify these structures in epithelial cells from defined basal, spinous and granular strata. Hamster cheek pouch mucosa from five animals was processed for electron microscopy using strictly standardized techniques and a stratified random sampling procedure was used to obtain micrographs of cells from basal, spinous and granular layers. Stereological intersection counting techniques were used to determine for each layer the relative surface area of plasma membrane occupied by desmosomes (Ss), the number of desmosomes per unit surface area of plasma membrane (Ns), the mean individual desmosomal diameter (delta) and the mean individual desmosomal surface area (s). In addition, estimates of nuclear volume were obtained by direct measurement of nuclear profiles and volume-to-surface ratios were obtained by a combination of point and intersection counting, which enabled estimates for the volume (Vcell) and plasma membrane surface area (SPM) of the 'average' cell within each stratum to be acquired. Using this information, it was then possible to calculate both the total surface area (S) and the number (N) of desmosomes on the plasma membranes of average cells. The parameters Ss and Ns showed progressive increases between basal and granular layers, whereas values for delta and s were lower in granular cells when compared with basal and spinous cells. The parameters Vcell, SPM, S and N all increased progressively and significantly during differentiation. Between basal and granular layers, the mean cell volume and surface area had each increased approximately threefold, whereas the surface area and number of desmosomes on the average cell plasma membrane had increased approximately seven- and eleven-fold, respectively. Granular cells thus possess more numerous desmosomes, which occupy a greater proportion of the plasma membrane area but which are individually smaller, when compared with basal and spinous layers.
复层鳞状上皮中的桥粒在分化过程中似乎呈现出数量上的变化。在这项研究中，我们使用体视学和其他形态测量方法来量化来自明确的基底层、棘层和颗粒层的上皮细胞中的这些结构。对五只动物的仓鼠颊囊黏膜采用严格标准化技术进行电子显微镜处理，并使用分层随机抽样程序获取基底层、棘层和颗粒层细胞的显微照片。采用体视学交叉计数技术来确定每层中桥粒占据的质膜相对表面积（Ss）、单位质膜表面积上的桥粒数量（Ns）、单个桥粒的平均直径（δ）和单个桥粒的平均表面积（s）。此外，通过直接测量核轮廓获得核体积估计值，并通过点计数和交叉计数相结合的方法获得体积与表面积之比，从而能够获取每层中“平均”细胞的体积（Vcell）和质膜表面积（SPM）估计值。利用这些信息，进而可以计算出平均细胞质膜上桥粒的总表面积（S）和数量（N）。参数Ss和Ns在基底层和颗粒层之间呈现出逐渐增加的趋势，而与基底层和棘层细胞相比，颗粒层细胞中的δ和s值较低。在分化过程中，参数Vcell、SPM、S和N均逐渐且显著增加。在基底层和颗粒层之间，平均细胞体积和表面积各自增加了约三倍，而平均细胞质膜上桥粒的表面积和数量分别增加了约七倍和十一倍。因此，与基底层和棘层相比，颗粒层细胞拥有更多的桥粒，这些桥粒占据质膜面积的比例更大，但单个桥粒较小。
