Specimens of articular cartilage were obtained during surgical operations from the lateral condyle of a normal femur and from the head of the radius and the femoral condyle of rheumatoid patients. The specimens were fixed in 10% formalin, dehydrated in acetone, dried in air and coated with carbon and gold to be observed in a scanning electron microscope.
1. The surface of the normal cartilage showed parallel ridges of 5-7μ width densely netted by fibrils of 0.1-0.3μ thickness. It was emphasized that these probable collagen fibrils were naked in the cartilage surface.
2. In the rheumatoid cartilage surfaces sheets of fibril nets were partly desquamated and the cartilage substance was irregularly excavated presumably by an elevated action of lytic enzymes. Granules of unknown nature abundantly occurred on the fibrils.
3. This study proves the applicability of scanning electron microscopy to the ultrastructure research of the cartilage surface in normal and pathological conditions.

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By using ferritin as a tracer of protein transport, the effect of the renal extracts on the blood-brain barrier was studied by electron micrscopy. In the endothelial cells of the capillaries of the cerebral cortex a marked increase in pinocytotic activity was demonstrated when the extract of ischemic rat kidney was injected to the bilaterally nephrectomized rat. Bilateral nephrectomy alone did not cause this effect. The ferritin particles were found mainly in the pinocytotic vesicles, caveolae intracellulares, and occasionally free in the cytoplasmic matrix of the endothelial cells, but not in the intercellular junctions. The basement membrane appeared free to transport the ferritin particles directly.
It was concluded from these findings that the vascular permeability factor of renal origin might affect the cerebral capillaries by exclusively accelerating the pinocytotic activity of the endothelial cells.

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The osmiophilic specific granules of the atrial muscle cells were electron microscopically examined in the atria of the rat, mouse, guinea pig, dog, cat, rabbit, flying squirrel, pig, ox, monkey and man. In all the animals the granules were round or oval in shape and bounded by a limiting membrane. The content of the granules was moderately electron dense and changed its density with the use of different fixatives. Groups of granules were gathered in the perinuclear sarcoplasm but some were seen between myofibrils and beneath the plasma membrane. The material of the granules is believed to be condensed into visible granules in the Golgi complex and released by eruptocrine type secretion.
Certain differences in the distribution, the average diameter and the number per cell of the specific granules were recognized among different species. The atria of the rat and mouse contained a large number of the glanules with a large diameter. The dog and the cat showed a small number of small granules gathered in the perinuclear region. In the monkey and human atria the granules were considerably numerous though small in size. The granules in the atria of the ungulata (pig and ox) were sparce and dispersed all over the muscle cell. Some species differences in the electron density of the granules were also found. They are characteristically dense in the rabbit whereas much less dense in the mouse.
Experiments in the mouse confirmed our previous results in the rat in that the administration of reserpine caused a decrease whereas nialamide, L-DOPA and L-methyl-DOPA an increase of the atrial specific granules. Catecholamines were not proved in the granules by fluorescence method. The possible nature and significance of the granules were briefly discussed.

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The specific granules of the atrial muscle fiber in the rat were observed under the electron microscope and the effects of substances affecting the autonomic nervous system on the granules were examined.
Six to 24hrs after intraperitoneal administration of reserpine, the granules were decreased in number without showing morphological changes. In the cases of administration of such autonomic nerve-affecting drugs as L-DOPA, nialamide, isoproterenol, bethanidine sulphate and propranolol the granules were increased in all areas of the atriale muscle cell within several hours after administration.
On the basis of these experimental results, the relationship between these granules and catecholamine was discussed.

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At least six types of endocrine cells have been identified by light and electron microscopy in the gastrointestinal mucosa of the rabbit. Among them are two types of amine producing cells, the enterochromaffin and enterochromaffin-like cells, and four types of polypeptide producing cells. The pyloric G cells, very likely producing the hormone gastrin, and the functionally undefined X cells, mainly scattered in the fundic mucosa, have been characterized as gastric endocrine cells of the polypeptide type. Small granule cells (S cells), perhaps related to the hormone secretin, and large granule cells (L cells) of unknown function have been found scattered along the intestinal mucosa.
Reserpine (2.5-5mg/kg intraperitoneally) depleted the 5-hydroxytryptamine stores of the duodenal enterochromaffin cells, reduced the osmiophilia of their granules without evidently affecting their protein matrix and activated the Golgi complex. Enterochromaffin-like cells of the fundic mucosa were not markedly altered by the drug.

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The damage to spermatogenetic cells of mice following the application of Mitomycin-C (1.7 or 3.4mg/kg) was studied on some quantitative and histological bases with particular attention to the sensitivity of spermatogenetic cells of each population, and the results obtained were compared with those from X-ray-irradiated mice.
A remarkable decrease of spermatogonia, spermatocytes, spermatids and spermatozoa occurs in the order of their developmental stages at the 1st, 2nd, 3rd and 4th week after the treatment. Evidence presented implies that the sensitivity of spermatogenetic cells to the drug differs by their developmental stages.
The decrease of these cell types was more marked with the increased concentration of the drug. Their return to the control value in the 3.4mg/kg case is one week later than that in the 1.7mg/kg case.
It has been shown that spermatogonia are more sensitive than germ cells of other types, and that type B spermatogonia are higher in sensitivity than type A spermatogonia.
Spermatocytes show necrosis at the resting stage as well as in the process of division and chromosome aberrations at metaphase and anaphase. Evidence is available to show that some spermatocytes seem to participate in the formation of abnormal spermatids and spermatozoa, or otherwise, slough in the ductus epididymidis.
No pathological changes were observed to occur in spermatids and spermatozoa treated with the drug. Their depletion seems to be attributable to the obstruction of spermatogenesis due to the disappearance of spermatogonia.
Sertoli cells and interstitial cells show a gradual increase following the application of the drug suggesting a correlation with the shrinkage of seminiferous tubules.
The rate in decrease of the testis-weight after the treatment with the drug is more marked than that of the tubule-diameter. Further, the features involving decrease and recovery of the testis-weight and the tubule-diameter can be explained on the basis of the destruction and recovery of spermatogenetic cells.
Data so far presented make it possible to conclude that Mitomycin-C and X-rays seem to affect male germ cells leading to their ultimate damage in a generally similar manner. The relative dosage between Mitomycin-C and X-rays considered on the basis of disappearance and recovery rate of spermatogonia seems to be as follows: 1.7mg/kg of Mitomycin-C corresponds approximately to the dose of 300r of X-rays and 3.4mg/kg to the dose of 500r.

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