Being multipotent progenitor cells, mesenchymal stem cells continue to attract attention as a promising tool for cell-based therapy and tissue engineering. However, research on the ultrastructure of these cells is rather scarce. This study was aimed at the investigation of the transmission electron microscopic ultrastructure and morphology of mesenchymal stem cells isolated from the stroma of rat umbilical cord using the explant culture method. At the end of the third passage, some of the cells isolated from the stroma of the umbilical cord were harvested for electron microscopic examination. The remaining cells were induced for osteogenic, chondrogenic, and adipogenic differentiation. On the basis of the results obtained, it was concluded that mesenchymal stem cells derived from the stroma of the umbilical cord display morphological features similar to those of other types of mesenchymal stem cells and can be used as an alternative cell source in cell-based therapy owing to the advantages they offer.