[Historical review of development of neuro-historogical techniques and three-dimensional reconstruction of individual neurons].
The image of neuron proposed by Barker in 1899 is until now useful. However this image could be said to be only a schema based on the data obtained by various histological techniques developed in the latter half of the nineteenth century. Although thereafter many careful observations on neuronal architecture have been made, much still remains to be done for revealing their true geometry. In our histological analysis with Golgi-stained materials in the cat, it was found that the reflecting illumination showed the somal surface and its relationship with the dendrites in clear relief. With this method it was possible to develop a new approach for photogrammetric representation of the neuronal soma as well as for following the total course of dendrites in successive serial sections that had been cut off by the microtome knife. This has provided a means for estimating precisely the dimensions of the neuron. In addition, by means of the intra-axonally injection of HRP in cats, the intramedullary course of physiologically identified afferent fibers originating from various muscles in lumbosacral region was also reconstructed three-dimensionally from serial sections. The results thus obtained revealed that the collaterals belonging to groups Ia, Ib and II fibers of the muscles examined showed some typical differences in their courses and in their terminations in the gray matter. The results of extra-cellular injection of BDA (Sato F. et al., 2000) into the Nucl. subthalamicus in monkeys also cited as this sort of work. It should be emphasized that, whether classic manual method or more effective modern techniques are used, three-dimensional reconstruction is the most important factor for studying the comlete axonal geometry of individual neurons, of which effects may be said, at least at present, to be still methodologically incomplete.
Mannen
Hajime
H
Faculty of Medicine, Tokyo Medical and Dental University.
D000818:Animals; D001921:Brain / Q000166:cytology*; D002415:Cats; D006652:Histological Techniques / Q000266:history; D049672:History, 19th Century; D049673:History, 20th Century; D006801:Humans; D009462:Neurology / Q000266:history*; D009474:Neurons / Q000166:cytology