In the terminal portion of the bronchial tree of the dolphin lung the bronchioli, bronchioli terminales, respiratorii and alveolar ducts were identified. The simple cuboidal epithelium of the bronchioli respiratorii contained blood capillaries which appeared as if exposed directly to the bronchiolar lumen. In the wall of the bronchioli, down to the distal end of the bronchioli respiratorii, there existed numerous small cartilages. Numerous well-developed sphincters occurred especially in the wall of the bronchioli terminales and respiratorii at regular intervals and the bronchiolar lumen formed many large round dilations (ampullae) between the sphincters, which were communicated by constricted portions (isthmi) induced by the sphincters.
Each alveolar septum of the dolphin lung possessed two independent respiratory surfaces facing the neighboring alveolar lumina, which were completely separated by a thin continuous axial connective tissue layer. Both respiratory surfaces have their proper blood capillaries and alveolar epithelial cells respectively.
The cuboidal alveolar epithelial cells were classified into small and large ones, of which only the former protruded the thin cytoplasmic projection covering the alveolar surface of the blood capillaries. The large cytoplasm-rich cells might be transformed into round alveolar phagocytes storing a large amount of fat droplets and scant dust particles which they might have probably taken up from the blood and inhaled air respectively. Similar transformation and fat storing were also sometimes observed in the simple cuboidal epithelium of the bronchioli. These epithelial alveolar phagocytes were easily detached from the alveolar wall into the alveolar lumina. Besides, there existed mesenchymal histiocytes; those in the connective tissue of the alveolar septa and in the small lymphoid tissue found in the bronchiolar mucosa stored mainly dust particles, while those in other connective tissue portions stored mainly fat droplets as did the alveolar phagocytes. Thus the amount of fat droplets stored in epithelial and mesenchymal phagocytes exceeded in general by far that of dust particles, the latter being as compared with that in other common mammals, extraordinally small. These morphological facts suggested on the one hand that the dolphin lung may participate much in fat metabolism and on the other that the air contamination on the sea surface, where the dolphin lives, may be very low.
In the dolphin lung the development of the elastic tissue was not particularly good. The thick elastic strands found in the wall of the alveolar duct contained few smooth muscle fibers. The functional significances of the bronchiolar cartilages and sphincters were also discussed.

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The light microscopic structure of the papilla foliata from adult rabbits was studied three-dimensionally. Use was made of Epon embedded serial sections 0.5 to 1.0μ thick prepared by an ultramicrotome and stained with 0.5% toluidin blue in a buffer solution of MILLONIG. The results obtained were as follows.
1. The distribution and arrangement of the type I (gustatory) cells and the type II (sustentacular) cells in the taste buds were fairly uniform as well as regular. The type II cells distributed uniformly in the taste bud were always surrounded by two to four cells of type I cells which were relatively small in size. Observation of the vertical or diagonal sections passing the canal of a taste bud revealed light (type II) cells and dark (type I) cells alternatively arranged in the upper half of the organ.
2. The presence of cells in mitosis was recognized in the taste buds; these cells showed an arrangement of chromosomes characteristic of the anaphase stage, and were in structure, size and stainability, very akin to the type II cells.
3. Occurrence of the binucleate cells was observed exclusively in type II cells; and these twin nuclei showed all the features suggesting amitosis.
4. The size of the taste buds showed a wide variation (15-60μ). Among the large sized, there occasionally occurred taste buds with two pores.
5. A conclusion was drawn from the foregoing results that proliferation of the taste bud cells did not depend solely on the development of the peripheral epithelium, but to some extent on the division in situ of the taste bud cells themselves.

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In a study of the experimental brain edema using the balloon-compression method, unusual axons characterized by numerous mitochondria, vesicles, dense bodies, amorphous material and neurofilaments were demonstrated by electron microscopy. According to their structural features which associated with the stages of the brain edema, the unusual axons were classified into eight types. It was suggested that type I and II might transform to type IV and V by way of type III. The unusual axons accorded in many structural respects with those of nerve degeneration reported in the past. Therefore it was suggested that the unusual axons were closely related to the nerve degeneration, which was supported by the results of the light microscopic observation in the present study.
The appearance of the unusual axons may be attributed to the metabolic alterations of glial cells induced by the brain hypoxia or cerebral circulatory disturbance following the compression by which the nourishment of nerve cell may be disturbed.

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The livers from 20 patients two to six months of age, with congenital biliary atresia and from 7 control babies were studied by means of electron microscope. Embryonic livers of 15 human fetuses were also examined.
A characteristic feature of the liver cells in congenital biliary atresia is the presence of anomalous microvillous cell borders which line the elongated perisinusoidal and extensively developed intercellular space. Displacement of nucleus and rugged shape of the hepatocyte are considered to be another striking feature in congenital biliary atresia.
Observation of the normal embryonic liver indicates that in the 6-week fetus, the hepatocytes are already arranged to contact with each other with usual 100Å wide intercellular space as seen in the adult liver.
It is suggested that the malformation of the bile duct and the surface change of the hepatocyte described in the present paper may be caused at the same embryonic stage by the action of a teratogenic factor as coupled abnormalities of the cells in congenital biliary atresia.

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The intestinal mucosa of the Elaphe quadrivirgata was studied by electron microscopy, in order to reveal the absorption mechanisms from the view point of comparative anatomy. Three types of cells were distinguished in the epithelium: columnar, goblet and argentaffin cell. The columnar cells of the mid-intestine take the leading part in the absorption of nutrients. The apical cytoplasm of the columnar cell of the end-intestine is filled with membrane-limited granules which seem to be secretory in nature. The goblet cells are quite similar to those of the other vertebrates in the morphological feature. The argentaffin cells are characterized by the presense of specific granules. Small osmiophilic materials were detected in the Golgi complex and in the dilated space of the granular endoplasmic reticulum, and it was suggested that the Golgi complex and the granular endoplasmic reticulum may play significant roles in the formation of the specific granules of the argentaffin cell. Unique intramitochondrial inclusions are the most interesting feature of the epithelium. One of the snakes contained aggregated small vesicles inside the nuclei of the intestinal epithelium, the functional significance of which is not known at present. No fenestration was observed at the capillary wall of the lamina propria.

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