Objectives The aim of this research was to study the intensity of cytokeratin 17 (CK17) in the parenchymal elements of rat’s submandibular salivary glands subjected to fractionated radiotherapy regimen that used for treatment of head and neck malignancy. Materials and Methods Twenty male albino rats were divided into two equal groups (normal and irradiated). The irradiated group received a radiation dose of 5 Grays daily for 5 days using therapeutic X-ray beam. Six months later, submandibular gland was dissected out and prepared for both histological and immunohistochemical studies. Results Submandibular gland of irradiated group showed two different types of histological alterations. The first alteration showed severe gland atrophy replaced by either fibrous or fatty tissues. In some sections, the gland exhibited proliferating activity in the form of profuse amounts of mitotic figures. Immunohistochemical examination of control glands displayed a mild cytoplasmic expression of CK17 of duct cells as well as serous acini. The staining pattern was either diffused or concentrated at the basal part of the cell with negative expression at its apical part. Statistical Analysis Expression of CK17 in submandibular gland of irradiated group displayed a highly significant differences (P < 0.001) in both intercalated and striated ducts. Many serous acini displayed a highly significant differences (P < 0.001) whereas, mucous acini were negatively stained. Conclusions The intensity and diffusion of CK17 expression in our results foretell the pathological effect of radiotherapy on the intermediate filaments of salivary gland parenchyma that interfered with production and/or secretion of saliva leading to xerostomia.

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INTRODUCTION:Stem cells constitute the source of differentiated cells for the generation of tissues during development, as well as for regeneration of tissues that are diseased or injured postnatally. The stem cell research has grown exponentially to improve the life of patients with conditions that span from Alzheimer's disease, cardiac ischemia to bone or tooth loss. In dentistry, stem cell biology and tissue engineering are of great interest since they may provide an innovative for generation of clinical material and/or tissue regeneration. Mesenchymal stem cells were demonstrated in dental tissues, including dental pulp, periodontal ligament, dental papilla, and dental follicle. These stem cells can be isolated and grown under defined tissue culture conditions and are potential cells for use in tissue engineering including dental tissue, nerves and bone regeneration under appropriate conditions. This review was performed to study the concepts of stem cells and the most recent application of dental stem cells.

Background and aim: In normal stratified squamous epithelia, syndecan-1 works as cell adhesion molecule, and exhibits an important role in the regulation of cell growth and differentiation during the development. It is recognized as tumor marker with diagnostic and prognostic role in different cancer types. This study was planned to explore the role of syndecan-1 in oral squamous cell carcinoma. Materials and Methods: Twenty two cases were histologically diagnosed as Oral SquamousCell Carcinoma (OSCC) that simultaneously contained dysplastic epithelium and carcinoma in situ (CIS) foci. Immunohistochemical staining for syndecan-1, alpha smooth muscle actin and Ki-67 were done.Results: Decreased expression of syndecan-1 from normal epithelia to CIS. In OSCC parenchyma, transition from cell membrane localization into cytoplasm was detected. In addition, strong expression of syndecan-1 in stromal fibroblasts was observed. Conclusion:Decreased expression of syndecan-1 in parenchymal cells together with its appearance in stromal fibroblasts might be used as a reliable tool in oral squamous cell carcinoma early diagnosis.