Abstract
Tissue flap (here called as large section) of coronal cut of the cerebral hemisphere or the both hemisphere from autopsied material is fixed with formalin, embeded in celloidin or paraffin, sliced into 5-20u thin section, and stained by various methods for the central nervous system. The above procedures have been employed as routine works. It is disadvantage to take a considerably long time (about 2 months) from fixing to finishing preparation of the large section. On the other hand, it is advantage to observe lesion as a whole in the large section. In histopathological examination of the brain nervous tissue as a routine, the preparation is usually made from many small section cut from various parts of the brain tissue. In examination of small sections collected from many specimens, however, findings on the every sections have to be reconstructed to assume the whole picture; but the reconstruction might lead one to a wrong assumption. Taking an example of the myelin sheath in histopathological examinations of organic diseases of the ceptral nervous system, macroscopic observation of lesion is often more significant rather than observation of fine structure of the myelin itself. It is considered that the histopathological value in use of large section cover the disadvantage in time consumption for its preparation. For this paper, macroscopic observations were made on the staining condition by ages of the myein sheath, applying the advantage of large section to observe the cut surface of brain. It is said that the formation of the myelin sheath progressed with age development, in human the progress is remarkable in 2-3 months after birth and reaches to the peak in about 5 years old, and then the progress curve makes a constant level. The brain without clinical and macroscopic lesion was used. The coronal cut-surface was made at the level of corpus mammillare. Kluever-Barrera method was employed to simultaneously stain the nerve cell and myelin sheath. Stain of the myelin sheath is already seen from the internal capsule to the cerebral peduncle in 13 hours after birth, its concentration and extent increases with growth, and the stain degree of the one-year-old brain is not differ from the adult one. In examination of the myelin sheath by staining, it is necessary to keep constant the thickness of the cut-surface and section. Even with the brain tissue of the same age (especially of newborn infant), the stain degree is not the same by the difference of tissue parts. It is suggested that presentation of a constant stain degree in any part of the cut surface as well as in the adult will be seen in the 3 to 5-year-old brain containing lipids at the highest level, which is important for the formation of the myelin sheath.
