Histopathological studies of ameloblastoma of the jaw were made in a total of 41 cases in connection with clinical aspects. In addition, electron microscopy was carried out in limited cases for exploration of the cell origin.
Based on the predominant pattern of growth and the grade of differentiation of parenchymal epithelial cells, cases were classified histologically into two categories; plexiform and follicular. Of 41 cases examined, 18 were of plexiform type and 13 of follicular type. The remaining 10 cases displayed mixed follicular and plexiform patterns and were classified as mixed category.
In the plexiform type, the epithelial cells formed anastomosing cords or strands with a variable amount of stroma. The cells appeared undifferentiated and irregular in shape. In the follicular type, the epithelium formed more or less discrete islands. The cells making up the peripheral zone of the islands were columnar in shape with the nuclei appearing to be polarized away from the basement membrane. The central area was composed of a loose network of cells resembling stellate reticulum of enamel organs. Squamous metaplasia, formation of keratinized pearls and colloid cystic degeneration were frequently noticed in the center of the follicular islands. In addition to the presence of both plexiform and follicular patterns in the same tumor, epithelial islands with transitional features were also found in the mixed type. Squamous metaplasia and cystic degeneration were often noticed both in the follicular and transitional islands.
Cases with follicular and mixed variants were detected in adolescence and adult, whereas those with plexiform type occured mostly in childhood and adolescence. Ten cases were found to develope at less than 20 years of age. Microscopically, all of them were of plexiform type.
Grossly the plexiform type of ameloblastoma appeared as a solid mass or sometimes wholly cystic. In follicular and mixed types the lesions were mostly multilocular. It appeared that the size of the lesions was generally larger in plexiform type than in other two types at the time of surgery. Among 41 cases examined, there were 7 cases with recurrent ameloblastoma. All of them were grossly multilocular. Microscopically, 5 of them showed the features of follicular type and the other two were classified as mixed type.
In electron microscopy, the epithelial islands of follicular type displayed a distinct zonal arrangement and were composed of three layers, peripheral, intermediate and central. The peripheral layer consisted of a single row of columnar cells with the nuclei displayed away form the basement membrane, which the cells rested upon. The cytoplasm contained variable amounts of mitochondria, granular endoplasmic reticulum and aggregates of glycogen granules. Tonofilaments were few in number. Intercellular spaces between the lateral surfaces of the cells were generally narrow. The desmosomal connections were seen only occasionally. The intermediate and central zones were composed of cells, stellate or polyhedral in shape, with elongated anastomosing cell processes. Desmosomes were demonstrated where the cells were in close contact with each other. The cytoplasm contained bundles of tonofilaments. The peripheral cells had a superficial resemblance to the ameloblasts of enamel organs, but the features characterising the fine structure of the ameloblast in the stage of matrix production, such as Tomes process, well developed Golgi apparatus, complex granular endoplasmic reticulum and of secretory granules were not evidenced. The peripheral cells comprising the epithelial islands with transitional features in the mixed type similar displayed fine structure to those found in follicular type.

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Using the horseradish peroxidase (HRP) technique, the autonomic preganglionic neurons which project onto the uterine wall were studied on the female rat.
Following injection of an HRP solution into the uterine wall, the intramural postganglionic neurons were discovered in the myometrium near the basement of the bicornuate uterus.
In 6 experiments, an HRP solution was injected into the site of the intramural postganglionic neurons. After a survival period of 2 days, the lumbar and sacral cords were serially sectioned and processed for histochemical demonstration of HRP.
Of the total of 3939 HRP labeled cells, 885 (22%) were observed in the lumbar regions (L1-L3) and 3054 (78%) in the sacral regions (L6-S2). The HRP labeled cells were distributed in 4 nuclei ; 1. nucleus intermediolateralis pars principalis (ILp); 2. nucleus intermediolateralis pars funicularis (ILf); 3. nucleus intercalatus (IC); 4. nucleus dorsalis commissuralis (DCN).
The total of 885 HRP labeled cells observed in the lumbar regions were distributed over 4 nuclei : 1. 621 (70%) in DCN ; 2. 215 (24%) in ILp ; 3. 34 (4%) in IC ; 4. 15 (2%) in ILf. This indicates the DCN is the major site of sympathetic preganglionic neurons projecting onto the uterine wall. On the other hand, the total of 3054 HRP labeled cells observed in the sacral regions were distributed over 3 nuclei : 1. 2757 (90%) in ILp ; 2. 213 (7%) in IC ; 3. 84 (3%) in ILf. This indicates the ILp is the major site of parasympathetic preganglionic neurons projecting onto the uterine wall.
The laterality of distribution of the HRP labeled cells was clearly recognized in the sacral regions, but not in the lumbar regions. This indicates the sympathetic preganglionic neurons innervate bilaterally, but the parasympathetic ones ipsilaterally.
According to the criteria whether or not the HRP labeled cell can be expressed by oval, fusiform, pyramidal or multipolar form, the HRP labeled cells were classified into 2 groups, the morphologically classifiable (47% of the total) and unclassifiable (53% of the tatal). In common with both sympathetic and parasympathetic preganglionic neurons, the majority of the HRP labeled cells showed fusiform, and the minority of them showed oval, pyramidal and multipolar. The relation between form and role of the autonomic preganglionic neuron may be an important problem which should be answered in future.

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The methods generally used in the second step screening of mass survey for gastric cancer are the direct, routine x-ray examination and/or the endoscopic examination. In order to improve the accuracy and efficiency of close examination (the second step examination), the results with two methods of close examination and in the institutions where they were carried out were respectively compared each other in the point of the detection rates of gastric cancer. The receiving rates of close examinations were also compared between the x-ray and the endoscopy, and between our institution and the others respectively.
The results obtained from this study are as follows ;
1) A total number of subjects receiving the first screening was 79064 and 29.9% of them was required to receive the close examinations.
2) A number of subjects required to receive the endoscopic examination was 16134, showing eleven times more than the x-ray examination.
3) A receiving rate of the close examinations was 77.4% in our institution and 69.9% in the others.
4) In comparison of institution, a receiving rate of the endoscopy was 77.4% in ours and 61.1 % in the others. That of the x-ray was 76.7% in ours and 311.9% in the others.
5) Regarding a detection rate of gastric cancer, our institution showed 1.1% with each methods of the close examinations, but the others revealed 0.3% with the x-ray and 0.7% with the endoscopy.
6) A ratio of early stage cancer to the detected gastric cancer was 60.2% in our institution, but 40.5% in the others.
From these results, the followings are concluded ; Compared with the other institutions, our institution obtained excellent results in the detection rates of gastric cancer as well as the receiving rate of close examinations. For the reasons, these are considered that, at first, the x-ray examination in our institution was less used than most of others ; second, most of the persons indicated to receive the endoscopic examination were examined with the x-ray instead of the endoscopy in the other institution.

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A case of lymphangiomyomatosis was reported. The patient was a 33-year-old woman with the chief complaints of dyspnea, cough and abdominal swelling. Lymphnode enlargement was detected and inguinal lymphnode was examined with imprint technique, light and electron microscope.
1. In the imprint preparation, there were papillary and flat tumor cell clusters. The former was composed of polygonal tumor cells and the latter of spindle-shaped ones.
2. Histologically, anastomosing cords of tumor cells were separated by endothelial-lined channels, which contained a few lymphocytes. In some areas the tumor cells composing the cords were round and contained round-oval, vesicular nuclei with distinct nucleoli. In other areas, the tumor cells were eosinophilic and spindle in shape, with elongated nuclei. With PTAH and Mallory stain, fine myofibrils were visible. The nuclei were not atypical and showed no mitotic figures. Tumor cells were often surrounded by delicate reticulin fibers, but elastic and collagen fibers were not seen.
3. Ultrastructurally, two kinds of tumor cell populations were noted. One of them was comparable to relatively mature smooth muscle cells. The cytoplasm was spindle in shape and had abundant myofilaments, dense bodies, and pinocytotic vesicles. Other cytoplasmic organelles were scanty. The other type of cells seemed to be primitive smooth muscle cells. The nuclei were round-to-oval and had a rare indentation. Large amount of glycogen can be seen in the cytoplasm. Rough endoplasmic reticulum, free ribosomes and mitochondria were sometimes present. Prominent Golgi apparatus and numerous high electron dense granules were found in some cells, but myofilaments were small in amount. Cytoplasmic processes were prominent showing interdigitaion in these cells.
The present observations seem to suggest that lymphangiomyomatosis is the lesion of hamartomatous proliferation of the smooth muscle cell of the lymphatics.

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