The pituitary gland is constituted by several cell lines whose function must be carefully regulated in order to guarantee that all the complex neuroendocrine activities are controlled. Recent scientific advances allow us to study the development and pathologies derived from an altered pituitary embryogenesis. Some of these genes (e.g., BMP, FGF, Lhx, etc.) are related to the morphogenesis of the whole body and are expressed with similar patterns among other species and animal models. Other genes, such as Pit-1, and homeodomain proteins are expressed regionally to generate specific cell lines, while hormonal factors and genes are activated locally to generate the final phenotype of the cell. Current knowledge allows us to study the origins of human hypopituitarism and tumorigenesis. This review covers the basic principles and most common genes mentioned in the literature so that residents and attending physicians that are not usually in contact with patients affected by this pathology can learn basic information before reading more specific texts. DOI: 10.24875/RME.20001946