[Ultrastructural localization of cytochrome oxidase in human embryonic brain cells]

The author studied ultrastructural localization of cytochromoxidase (CO) in neuroectodermic cells (young neurons and glioblasts) of the brain of human embryos and 7--10-week-old fetuses. Use was made of CO determination via cytochrome C with the aid of 3,3'-diaminobenzidine as an electron donor. Intracellular distribution of CO in young neurons did not differ from that in glioblasts. Ultrastructural localization of activity appears to depend on the time of embryonal development and may be settled by varying the histochemical reaction conditions. CO was shown to be detectable in mitochondria of 7-week-old embryos and in mitochondria, some parts of cytoplasmic membrane, and in the cytolemma, that forms primary cell contacts, of 8--10-week-old embryos and fetuses. Ten weeks of embryonal development are supposed to be a time for cytochrome system maturation in the most active parts of the cytoplasmic membranes relevant to specific activity in future.