Genealogy of the anterior pituitary gland: Tracing a family tree

The anterior lobe of the pituitary gland is derived from the oval ectoderm early in gestation. A variety of techniques have been used to understand ho w early precursor cells differentiate to form the five major cell types tha t populate the adult anterior lobe. Current evidence suggests that corticot ropes arise from a lineage distinct from that of the other four cell types. The cells of the other lineage branch - thyrotropes, gonadotropes, somatot ropes and lactotropes - appear to be related because of their dependence on common transcription factors and the frequent occurrence of cells that pro duce multiple hormones. While thyrotropes arise through two routes, the lin eage related to somatotropes and lactotropes appears to be the most importa nt for hormone production. Each cell type can populate the organ and functi on in the absence of the of her cell types, except for lactotropes, which h ave a strong dependence on somatotropes. Our current knowledge of anterior pituitary cell lineage relationships may contribute to a better understandi ng of the origin of pituitary adenomas and tumors.