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Comparative Anatomy, Physiology, and Biochemistry of Mammalian Skin
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
The stratum granulosum (stratum intermedium) cells possess compact tonofibrils with dense staining regions which are irregular in shape (keratohyalin). Most tonofibrils are not discernible until they are transformed into keratohyalin. These keratohyalin granules may not be present in all of the stratum granulosum cells. If they are not present, then there exists fibrous substance in the basal and spinous layers. The keratohyalin granules exhibit differences in their appearance. They may be homogeneous or may exhibit a distinctive pattern of light and dark areas. They are usually associated with filaments and ribosomes. These keratohyalin granules become enlarged as the cells approach the surface. At this time, membrane-coating granules are seen to migrate toward the cell plasmalemma, fuse with it, and release their contents into the intercellular space. Organelles disintegrate and filaments arrange themselves into bundles.
Odontogenic Epithelium and its Residues
Published in Roger M. Browne, Investigative Pathology of the Odontogenic Cysts, 2019
Progression from the bud to cap stage leads to differentiation of four regions in the enamel organ; (a) inner enamel epithelium: low columnar cells; (b) outer enamel epithelium: low cuboidal cells; (c) stratum intermedium: squamous shaped cells; (d) stellate reticulum: stellate shaped cells. The inner and outer enamel epithelium are continuous at the cervical loop and are derived from the basal cells of the tooth bud. This histogenesis appears to be controlled by epithelial-mesenchymal interactions since it has been shown that outer enamel epithelium can acquire the histogenic specificity of an inner enamel epithelium when cultured in heterotopic association with dental papilla.22 In such an association, a new stratum intermedium was observed in contact with the newly differentiated inner enamel epithelium reinforcing the concept of the interdependence of these two cell layers upon one another. It has been postulated that the epithelial-mesenchymal interactions involved in these histogenic modifications are matrix mediated through the dental basement membrane, which controls the cell kinetic changes and histogenesis.22,23 The extent to which tooth histogenic properties can be conserved by isolated cells is still in question.24,26
The Cell Biology of Amelogenesis
Published in Colin Robinson, Jennifer Kirkham, Roger Shore, Dental Enamel, 2017
Ziedonis Skobe, Doris N. Stern, Kenneth S. Prostak
The stratum intermedium is interposed between the stellate reticulum and the ameloblasts (Figures 5, 6, and 8). In the rat, the stratum intermedium consists of a single layer of cuboidal, closely packed cells connected to each other and to the ameloblasts by desmosomes and adherent junctions.65,69 In other species, stratum intermedium cells are pleomorphic, loosely packed, and may consist of several layers (cat,67 monkey,68 ferret, human,27 mini-pig42).
The Genes Involved in Dentinogenesis
Published in Organogenesis, 2022
Shuang Chen, Han Xie, Shouliang Zhao, Shuai Wang, Xiaoling Wei, Shangfeng Liu
The stratum intermedium is a highly dynamic and SHH-expressing structure that undergoes marked and transient changes in the histological organization and phenotype during odontogenesis. The stratum intermedium is involved in the development of the tooth germ, which has not been previously reported.151 This delicate cell group has undergone an amazing process of evolution and degradation, which is closely related to the process of development from the dental cusp to the cervix. SHH is one of the signaling molecules for which the intermediate layer may play a role in mediated its function.151 The primary cilia are essential for the integration of Wnt and Hh signals and in their functional absence, SHH signals decrease in the dental stroma, whereas those of Wnt increase in the dental mesenchyme.67
Vacuolar protein sorting 4B regulates the proliferation and odontoblastic differentiation of human dental pulp stem cells through the Wnt-β-catenin signalling pathway
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Yuhua Pan, Ting Lu, Ling Peng, Zhao Chen, Meiyi Li, Kaiying Zhang, Fu Xiong, Buling Wu
To examine the expression and localization of VPS4B, we first performed immunohistochemical staining of the front sections of a murine first mandibular molar on PN1, PN3, PN5 and PN7 (Figure 1). We found that during dentin development (from PN1 to PN7), VPS4B was highly expressed in the dental pulp cells near odontoblasts. At the late bell stage (PN1), VPS4B was also mildly expressed in the stratum intermedium and odontoblasts and weakly expressed in the stellate reticulum (Figure 1A-a). At the stage of hard-tissue formation and mineralization (from PN3 to PN5), VPS4B was consistently expressed in dental pulp cells, preodontoblasts and the stratum intermedium (Figure 1B-b,C-c). In contrast, the cells of the stellate reticulum stained only weakly while the odontoblasts tested negative for VPS4B (no staining; Figure 1B-b,1C-c). When dentin was formed (PN7), VPS4B was intensely expressed in dental pulp cells (Figure 1D-d).