Thymus medulla (rat, neonate)

Electron microscopy. An interdigitating cell in the thymic corticomedullary region shows a large electron-light cytoplasm with a complex branching (7) at the periphery. The nucleus is sectioned twice (1). There is abundance of organelles as well as of quite uniform electron-dense lysosomal structures (2) and small curved dense tubulovesicular structures. (4) black arrows point to Golgi areas. (3) region of the centrosome. (5) part of a blood vessel (5) with endothelium (5a) and an apposing pericyte (8). (6) medullar epithelioreticular cells with intermediate filaments (keratin filaments,*).