Annals of RSCB Vol. XV, Issue 2 142 DIFFERENTIATION OF PLURIPOTENT MOUSE EMBRYONIC STEM CELLS LINE Emoke Pall 1 , Elen Gocza 2 , Olga Soritau 3 , C. Tomuleasa 4 , Zsuzsanna Lichner 2 , M. Cenariu 1 , I. Groza 1 1. UNIVERSITY OF AGRICULTURAL SCIENCES AND VETERINARY MEDICINE CLUJ-NAPOCA ROMANIA, FACULTY OF VETERINARY MEDICINE; 2. AGRICULTURAL BIOTECHNOLOGY CENTER, GODOLLO, GENETIC MODIFICATION PROGRAM GROUP, HUNGARY; 3. “PROF.DR.IOAN CHIRICUŢĂ“ ONCOLOGICAL INSTITUTE, CLUJ-NAPOCA; 4. UNIVERSITY OF MEDICINE AND PHARMACY “IULIU HAŢIEGANU” CLUJ-NAPOCA Summary Embryonic stem (ES) cells are derived from the inner cell mass (ICM) of blastocysts. They are pluripotent cells that have the ability to differentiate in to different cell lines. This study aims to demonstrate the differention potential of mouse embryonic stem cells (ESCs). As the first stage of differentiation ESCs were transferred to gelatin-coated plates, and after 24 hours cell aggregation were performed in hanging drops. After organization of embryoid bodies (EBs) were transferred in to gelatin-coated plates. Cultures were observed daily withan inverted microscope for the appearance of contracting clusters and neural filaments. Our data show the ability of pluripotent stem cells line, important sources for regenerative medicine. Key words: mouse, embryonic stem cells, pluripotent, differentiation pallemoke@gmail.com Introduction The generation of various differentiated cells from pluripotent embryonic stem (ESCs) cells, which is a renewable resource, provides insights for studying not only the mechanism of early development in vitro but also cell transplantation therapy (Anversa P., et al. 1991, Hajime S., et al. 2006). Embryonic stem cells (ESCs) are undifferentiated pluripotent cells (derived from the inner cell mass of blastocyst stage embryos and can be propagated in vitro indefinitely (Evans and Kaufman, 1981; Thomson et al., 1998, Aejaz et al. 2007) maintaining long-term self renewal and the capacity to give rise to all cell types in the adult body when subjected to the appropriate conditions (Conley et al., 2005). ESCs cells are viewed as a promising cell source for cell transplantation because of their unique ability to give rise to all somatic cell lineages (Thomson et al., 1998; Wobus, 2001; Draper et al., 2004). In culture condition, when factors that maintain the pluripotency of ES cells are removed, ES cells spontaneously differentiate into derivatives of the three embryonic germ layers: the mesoderm, endoderm, and ectoderm (Keller, 2005). The formation and early differentiation of embryoid bodyes (EBs) as a principal step in the differentiation of ESCs in vitro. ESCs cells cultivated as embryo-like aggregates, called embryoid bodies (EBs), differentiate in vitro into cellular derivatives of all three primary germ layers of endodermal, ectodermal, and mesodermal origin. ES cell lines develop from an undifferentiated stage resembling cells of the early embryo into terminally differentiated stages of the cardiogenic, myogenic, neurogenic, hematopoietic,