The enamel tubes of the jaw teeth of Pagrosomus major and Taius tumifrons, and the jaw and pharyngeal teeth of Semicossyphus retieulatus were observed usingground sections. The ground sections were examined with the telemicroscope using transmitted light and as microradiagraphs. The enamel tubes penetrated into the enamel perpendicular to its surface, and their diameters were widest at the outer surface, diminishing through the deeper layer. Each enamel tube ramified with two or more, branches which bend in various directions. The tubes terminated by bending and tapering long before they reached the dentino-enamel junction. The historadiographs show that the enamel tubes of these fish are true tubes. Correct focusing of the ground. sections seen with the high magnification possible with the television microscope shows. that the enamel tubules are real, and that the dark granules are due to an optical effect.or Becke line.The dentin of porgies and Semicossyphus were also examined, using ground sections with transmitted light and historadiographic methods. No peritubular hypercalci fied zone appeared in the dentin of these fish. Correct interpretation of photomicrographs, that is, by recognizing the Becke line, the ground sections of fish dentin show just as it does in human dentin, that there are no Neumann's sheaths or Tomes' fibers in this processed tissue
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