The precise origin and course of sympathetic nerve fibers in the fungiform papillae of the frog's tongue were investigated by the fluorescence method. Fluorescent nerve fibers were seen accompanying the blood vessels in the fungiform papillae. These fluorescent nerve fibers disappeared after cutting the glossopharyngeal nerve, but were not altered by cutting the hypoglossal nerve. Following ligation of the glossopharyngeal nerve, accumulation of yellowish green fluorescent material was found in the proximal portion of the ligated nerve. Accumulation of yellowish green fluorescent material was not observed after sympathectomy. These results suggest that sympathetic nerve fibers reach the fungiform papillae along the glossopharyngeal nerve.

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The ultrastructure of the external gill epithelium of the salamander, Hynobius dunni Tago, is described with particular emphasis on the development and degeneration of the epithelial cells, and also its phagocytosis by macrophages. Two basic types of surface cells, ciliated and non-ciliated, were observed in the epithelium of the primary gill bar and secondary gill filaments throughout larval life. Based on their cytoplasmic density and organization as observed by transmission electron microscopy, the non-ciliated surface epithelial cells could be distinguished into three subclasses: pavement cells with mucous vacuoles, club-shaped clear cells with numerous vacuoles, and mitochondria-rich cells. Furthermore, two other types of epithelial cells were noted: basal cells and Leydig cells.
During metamorphosis, both the ciliated and non-ciliated cells revealed prominent cytoplasmic vacuolation. In addition, ciliated cells lost their cilia. On the other hand, the pavment cells showed increased amounts of tonofilaments in their cytoplasm and progression of cornification. The basal cells did not degenerate, but their basement membranes became considerably thickened and undulating. Degenerating cells were neither contiguous at the epithelial surface nor sloughed, but were drawn inwards within the epithelium. However, phagocytizing epithelial cells were not observed. The intercellular spaces in the epithelium widened as metamorphosis progressed. Phagocytic macrophages with a strongly positive acid phosphatase or nonspecific esterase reaction in their heterophagic vacuoles were often seen in the intercellular spaces and in the subepithelial connective tissue. It is thought therefore that such macrophages may participate in the removal of degenerated cells, and the packing of cell debris in the macrophages results in external gill reduction in tadpoles.

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Spermatogenesis and morphological changes of spermatids during spermiogenesis in the cotton rat were observed in light and electron microscopes. The cycle of the seminiferous epithelium could be divided into 13 stages on the basis of acrosomal changes. The frequencies of stages from I to XIII were 7.3,6.2,10.9,7.4,9.1,11.9,12.2,9.1,5.9,4.3,3.7,6.7 and 5.3%, respectively. Four types of spermatogonia (A₁, A₂, B₁ and B₂) could be discerned by the observation of whole mount samples. The precursor of an acrosome was located between a round nucleus and a Golgi complex in a Golgi phase spermatid. The homogeneous acrosome gradually expanded along the nuclear membrane and surrounded a half of the round nucleus in later cap phase. Two types of ER were three-dimensionally discerned by scanning electron microscopy. In acrosome phase, the cell and its nucleus began to elongate and the acrosome was in close contact with the plasma membrane. Many peculiar structures, such as the junctional specialization, manchette, nuclear ring and radial body, appeared in developing spermatids in this phase. The nucleus became slender until the end of this phase. In maturation phase, the nucleoplasm of the elongated nucleus condensed to a greater degree. A large number of mitochondria gradually gathered in the middle region of the spermatid cytoplasm and arranged along the axoneme in later maturation phase. Conclusively, these morphological characteristics of developing spermatids were similar to those in other mammals.

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We demonstrated a new origin of chief cells in the swine fundic glands. 1. Besides the mucous neck cells, the characteristic cells of the swine fundic gland were found to be filled with strongly PAS-positive substance, and to differentiate into the chief cells. 2. The strongly PAS-positive cells were distributed between the chief cells and parietal cells, but not in the mucous neck cell zone or the upper portion of the glandular body. 3. The nuclei of the strongly PAS-positive cells were flat and extremely dark, while those of immature and mature chief cells were fairly clear and either oval or round. 4. Immature chief cells in the upper portion of the glandular body contained PAS-positive substance in the supranuclear portion, however, the corresponding cells in the middle regions of the glandular body did not despite the presence of strongly PAS-positive cells nearby. 5. Strongly PAS-positive cells in the glandular body were irregular in shape, while immature chief cells accompanying them were cuboidal. In the basal region of the gland, strongly PAS-positive cells and mature chief cells were either cuboidal or short columnar. 6. The PAS-positive substance in strongly PAS-positive cells was seen to gradually decrease in quantity with differentiation of these cells into mature chief cells. At the end-stage of this process, the substance became undetectable and a reticulate framework formed in the cytoplasm. Nuclei became quite clear and assumed a round or oval shape in the resultant mature chief cells. 7. Coarse, dark blue pepsinogen granules were detected in mature chief cells. Strongly PAS-positive cells also contained pepsinogen granules, but these were smaller in comparison and claret colored. 8. The differentiation of strongly PAS-positive cells into mature chief cells is thought to take place most actively in the base of the fundic gland, because cells containing variable amounts of PAS-positive substance were observed in this area, i. e. undifferentiated cells contain large quantities of PAS-positive substance, but progressively less and less as differentiation progresses. 9. It is presumed that immature chief cells originating from mucous neck cells do not differentiate in the basal portion of the gland since the former were not detected in this region. Probably, half-matured cells in the lower part of the glandular body (seen as small cells with reticulate frameworks) move to the glandular base where the transformation into mature chief cells is completed. 10. Despite the two origins of mature chief cells, from mucous neck cells or strongly PAS-positive cells, there were no differences in final histological and histochemical characteristics; all were large, either cuboidal or short columnar cells, and had fairly clear round or oval nuclei, a cytoplasmic reticulate framework, coarse, dark blue pepsinogen granules, and a negative reaction to PAS, AB (pH 2.5 and 0.5) and PAS-AB (pH 2.5). 11. Some strongly PAS-positive cells were AB (pH 2.5) negative, while others showed varying degrees of reactivity. These differences may be related to variation in the stage of differentiation of the same kind of cell. Such cells were distributed in the base portion of the glands. 12. The strongly PAS-positive cells reacted negatively to AB (pH 0.5). 13. Various reaction colors were produced by PAS-AB (pH 2.5) staining depending on the degree of reaction with AB (pH 2.5). It was presumed that red stained cells were the least differentiated. 14. Mucous neck cells reacted strongly with AB (pH 2.5 and 0.5), while immature chief cells were negative for these stains. 15. Staining with PAS-AB (pH 2.5) produced a violet colour in mucous neck cells and a red colour in immature chief cells. 16. A survey of previous investigations of the fundic gland in man, Japanese macaque, crab-eating monkey, dog, cat, rabbit, horse, cow, mouse and rat revealed no evidence for the presence of strongly PAS-positive cells such as those described here in the

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We studied the basal lamina of duodenal epithelial cells of Xenopus laevis during metamorphosis. During prometamorphosis (Stages 56-59) it was almost flat, except for areas where it curved along the many fingerlike processes present in the cellular base of epithelial cells. In the flat areas of basal lamina, a thin (50nm), low electron-dense layer of lamina lucida was identified. Next to it was a 50 nm layer of lamina densa with high electron density which curved along the cellular processes in what appeared as 2-3 layers. During the early stages of metamorphic climax (Stages 60-62), the curving of the basal lamina along the cellular processes was yet more extensive and layers of lamina densa, folded 2-4 times, predominated over single layers. In stage 61, the lamina densa further condensed by folding and the thickness of the basal lamina exceeded 1μm. In stage 62, a layer of lamina densa just below the cellular base of the epithelial cells was clearly visible; the condensed lamina densa beneath it gradually disappeared. During the later stages of metamorphic climax (Stages 63-66), the basal lamina became flat and the lamina densa exhibited only one layer. The thickness of the lamina densa was approximately 50 nm which was nearly the same as that of the primary epithelium during the early stages of prometamorphosis. The observed morphologic changes of the basal lamina during metamorphosis may be related to morphologic changes of the epithelium and underlying connective tissue, and the basal lamina may play an important role in these morphologic changes.

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