Chromogranin A immunoreactivity in epithelial cells of the thymus.

We have examined the localisation of chromogranin A (CGA) in rat thymus using immunocytochemistry. In the adult female animals we found CGA-like immunoreactivity in the epithelial cells in the subcapsular zone, the outer part of medullary region and associated with Hassall bodies. In pregnant rats more epithelial cells were immunolabelled, suggesting an increase in CGA synthesis during pregnancy. Our results indicate that CGA may be colocalised with the thymic hormones in the epithelial cells of some regions of the thymus.