Ultrastructure of homografts of the rat median eminence into the anterior chamber of the eye.

Median eminences (MEs) were transplanted into the anterior chamber of the eye and collected at times varying between 10 and 72 days. At 10 days, all axons had degenerated leaving behind a well-vascularized epitheloid glial organ. With increasing age of the grafts, the characteristic lipid inclusions in the glial cells diminished and even disappeared, and the clear ultrastructural distinction between ependymal (tanycytes) and other glial cells became difficult or even impossible. In both the perikarya and perivascular terminals, an increased number of membrane-bounded, pleomorphic, electron-dense granulated vesicles occurred, the significance of which is unknown. Regrafting of these transplants into various hypothalamic and hypophysial sites is expected to yield information on the function of the glial cells of the ME.