Characterization of embryonic stem cells: A special focus on farm animals

23-32Embryonic stem (ES) cells are derived from the inner cell mass of blastocysts. They grow indefinitely while maintaining the pluripotency in the presence of specific growth factors such as leukemia inhibitory factor. The molecular mechanisms for self-renewal of pluripotent cells and the role of various growth factors involved in self-renewal as well as differentiation are being deciphered. ES cells, in their undifferentiated state, are characterized by a distinct morphology and by the presence of a set of markers classified into intracellular and extracellular types. Expression of specific markers (surface and transcription based) is an important criterion for pluripotent or undifferentiated state of cells. The expression of these markers is found to be exclusive to a particular species. A thorough understanding of the expression of these markers and of factors or conditions for the long-term culture of ES cells, without compromising their pluripotency and a stable genetic make-up is very important for the production and maintenance of ES cells from different species of farm animals. In this review, we present an overview of characterization of embryonic stem cells in farm animals