1953 年 5 巻 2 号 p. 265-274
The author reported (1952) that the enamel lamellae in human teeth are nothing but the leaf-like and transparent non-structural membrane that has no enamel prism. Concerning the cause of the appearance of the enamel lamellae the author (1952) came to the conclusion that the enamel lamellae originates from the splitting of the enamel occurred physiologically in accor dance with the gradual increase of the dentinal exterior area after the formation of the toothcrown. Thenceforth the author, as the results of the study on the histological nature of the enamel lamellae, obtained the new histological findings of the enamel lamellae only in the teeth of cows out of various mammalian teeth examined.
That is to say, the enamel lamellae of a cow consist of both the enamel prisms and interprismatic substance that are lowcalcified. The appearance or growth of the enamel lamallae of a cow is usualy observed to start in the outer part of the enamel. There a physiological decalcifying phenomenon appears, then the decalcified calcium disappears, and replacing the decalcified calcium, a organic matter originated supposedly from the dental pulp or dentinal canaliculi is filled in. Such a physiological change occurring secondarily in the enamel makes progress gradually into the deeper and lateral part of the enamel neighboring the lamellated enaml and at last reaches a limit of growth.
In the lamellated enamel, however, the organic matter is always being added to, producing no vacuole and at the same time under such a phenomenon the structural crevices appear in the enamel lamellae diffusely. Finally under such a phenomenon the width of the enamel lamellae reaches a definite limit. In the physiological reason for the appearance of the lamellating phenomenon the author considers, is to keep in accordance with the gradual increase of the dentinal exterior area after the completion of the toothcrown.
Now the author will makes clear below what his present views are and how they are connected with what he mentioned before. It is supposed that the enamel lamellae in the teeth of various animals are not different at all substantially from one another, but there exist various lamellating degrees peculiar to the various kinds of animals.
Concerning the enamel lamellae in the teeth of men and other mammals except cows, their lamellating change progresses so much that the histological structures, that is to say, the enamel prisms and interprismatic substance, are not observed at all. Only in the enamel lamellae of cows are the lamellating change so slightly observed that both the enamel prisms and interprismatic substance are observed verv clearly. On the other hand concerning the order of the appearance of the enamel lamellae, the author considers that the enamel lamellae in the teeth of various animals appear in the same way as the above-mentioned one of cows.