Microscopy images of human bone cells (osteoblasts) stained with GIEMSA allowing to visualise the cells nucleus, nucleoli and cytoplasm. My PhD project is related to the evaluation of biocompatibility of ferritic stainless steels. In order to perform biocompatibility studies is crucial to understand the types of cells that are used for them. Staining cells allows for the observation of the cell morphology, and this is the most direct technique to identify cell type and screen if there is any problems with them. These particular pictures were taken in the context of a baseline experiment where I was studying the characteristics of foetal human osteoblasts (FHOBS) cells for better comprehension of their biology in vitro. The goal was to access if FHOBS were a valid in vitro model to evaluate the biocompatibility of metallic biomaterials to be used in bone implants. The image has been treated in Photoshop for color change and quality improvement.