Immunocytochemical localization of thyroglobulin in the endostyle of the anadromous sea lamprey, Petromyzon marinus L

Thyroglobulin (TG) was localized in the endostyle of the anadromous sea lamprey, Petromyzon marinus L. by means of the unlabeled antibody peroxidase-antiperoxidase immunocytochemical method. TG was found localized on the apical surface and within the cytoplasm of type 2c and 3 cells and in some type 5 cells. By identifying the cells of the endostyle immunocytochemically it may be possible to study more readily the events of endostylar transformation during metamorphosis.