Light-microscopic and microspectrofluorometric characterization of porphyrin-containing astrocytes in mouse optic nerve.
Fluorescence spectroscopy has been employed to investigate the emission spectrum of unusual orange-red fluorescence found in the mouse optic nerve. Comparison of the spectra obtained with those of a number of porphyrins used as standards (protoporphyrin, uroporphyrin, and coproporphyrins) shows that the autofluorescence excited at about 400 nm (Soret band) is due to the presence of a mixture of these or other porphyrins in the nerve. Phase contrast, dark-field, and light-microscopy techniques demonstrated that the fluorescence is emitted by dense, coarse inclusions in the cytoplasm of astrocytes. The inclusions also exhibit high activity of endogenous peroxidase, a heme (porphyrin)- containing enzyme, characteristic for process of phagocytosis. A possible participation of these astrocytes in phagocytosis is delineated.
D000818:Animals; D001253:Astrocytes / Q000166:cytology*; D008297:Male; D051379:Mice / Q000033:anatomy & histology*; D009900:Optic Nerve / Q000166:cytology*; D011166:Porphyrins / Q000502:physiology*; D013050:Spectrometry, Fluorescence
D011166:Porphyrins