In this research project, we aim to establish a system that enables in vitro observation of the marmoset brain development and to analyze the F0 generation. However, it is essential to obtain individual data to create an accurate in vitro model. As such, we will perform single-cell RNA-seq and spatial transcriptomic analyses of early marmoset individuals to obtain spatial-temporal data. Utilizing these in vivo data, we will ultimately integrate stem cell technology with marmoset embryo culture technology to analyze more physiological brain structures. Furthermore, these technologies are expected to be of great social significance in pre-clinical trials (animal experiments) for developing new treatments and new drugs, as well as an alternative method to accomplish “Replacement,” one of the 3Rs for animal experiments.