الفهرس 
Introduction & aim of the work
Basic Stem cell biologyOnly 14 pages are availabe for public view
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Abstract
SCs are unspecialized, small, and rounded cells with squat nucleus and scanty cytoplasm. whereas other types of cells in the body have a limited life span and die after time, SCs can reproduce forever and they can act as biological resurrection. SCs have two characteristic features: self-renewal and ability to differentiate into mature cells. The different sources of SCs include: ICM, fetal tissues, UCB, placenta, and adult tissues. SCs can be classified into: totipotent, pluripotent, multipotent, and unipotent SCs according to their potency, or into: embryonic, fetal, neonatal, and adult SCs according to their source. The potential role of SC in medicine can be divided into two main roles: in basic research and in regenerative medicine. Frontiers of SC therapy in otolaryngology include its possible role in TM perforations, inner ear regeneration, facial nerve paralysis, vocal fold scarring, and mucosal defects of cleft palate. Furthermore, there is a potential role of SCs from olfactory mucosa in neurogenesis. There are several studies demonstrating the possible application of SC therapy in reconstructive head and neck surgery such as in skin, soft tissue, auricular, LTR, TMJ, and craniofacial bone reconstruction. Moreover, human palatine tonsil appears as a new potential tissue source MPCs. Beyond the possible role of SC therapy in tissue repair in otolaryngology, the principles of SC biology can be applied to head and neck cancers. The safety, both short-term and particularly long-term, of SC technologies is largely unknown. Safety concerns to consider include, but are not restricted to, aberrant cell development and tissue contamination with infectious agents of foreign biological and non biological substances used in the laboratory during processing of the SCs. The presence of neoplastic SCs has been proposed as a source of neoplastic development, as well as the reason for the observed treatment failure in certain neoplasms. Research with h-ESCs has become entangled in ethical, political, and legal debates. The main concern is not the therapeutic possibilities or scientific research, rather the source of the cells. The difficulties facing SC research are based on technical difficulties, moral and religious regulations, and political regulations. However, a progression is likely to occur in the field of SC research in spite of moral and political regulations. World is on the door step of a new type of restorative therapy that goes beyond treating disease symptoms. Therefore, regenerative medicine using SCs holds great hope for millions of patients with degenerative diseases and injuries. Making each potential use of SCs promises revolutionary advances. Finally, the SC research should go forward because we simply will not know the answers unless we do it. Key words: Stem Cell - Otolaryngology