|Stem cells are unspecialized cells have the capability to develop into many different cells during early life and growth. These are undifferentiated cells involve in internal repair system and able to differentiate into specialized cell types such as muscle cell red, blood cell, or a brain cell. Thrombocytes are also called as blood platelets whose function is the coagulation of blood. These are the non-nucleus structures obtained from the megakaryocytes of the bone marrow, and then enter into blood circulation. The main function of thrombocytes is stopping bleeding. Review articles are the summary of current state of understanding on a particular research topic. They analyse or discuss research previously published by scientist and academicians rather than reporting novel research results. Review article comes in the form of systematic reviews and literature reviews and are a form of secondary literature. Systematic reviews determine an objective list of criteria, and find all previously published original research papers that meet the criteria. They then compare the results presented in these papers. Literature reviews, by contrast, provide a summary of what the authors believe are the best and most relevant prior publications. The concept of "review article" is separate from the concept of peer-reviewed literature. It is possible for a review to be peer-reviewed, and it is possible for a review to be non-peer-reviewed.