The ultrastructure of ciliary muscle was studied in an old, healthy crab-eating monkey. In the cytoplasm, large swollen mitochondria, interdigitated mitochondria, various types of myelin-like figures, dense coarse membranous structures, lysosomal dense bodies, round lipid-like bodies, transitional forms from lysosomal dense bodies to lipid-like bodies, lipofuscin pigments, whorl-like structures of agranular endoplasmic reticulum, coated vesicles, and multivesicular bodies were occasionally observed. Nexus was demonstrated between adjacent muscle cells.
In the ciliary muscle, such findings were not only unknown in the earlier studies on the monkey species, but also some were never reported in any other species. Most of these inclusions were thought to be associated with cellular aging in relation to the presence of lipofuscin pigments and their related bodies, while the whorl-like structures might indicate either another type characteristic of the aged ciliary muscle or unknown pathological degeneration of the muscle. In addition, the possible occurence or the cytological significance of these inclusions, especially lipofuscin pigments, lipid-like bodies, whorl-like structures, dense coarse membranous structures, and myelin-like figures in the ciliary muscle, were discussed.

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The glial cells of the cerebral cortex were examined and counted in 60-80g rats by light and electron microscopy and compared to those described in the corpus callosum by MORI and LEBLOND.
The oligodendrocytes represented about 50% of all glial cells in the cortex and were less numerous than in the corpus callosum. They showed the three subtypes, light, medium dense and dense described in the corpus callosum. The cells seemed to be less variable and more rounded with less dense chromatin and more numerous microtubules than in the corpus callosum.
The astrocytes were also less variable, had somewhat less cytoplasm and shorter processes with fewer bundles of filaments than those in the corpus callosum. They comprised about 35% of all cerebral glial cells.
The microglial of the cortex was classified into interstitial and pericytal as in the corpus callosum. The interstitial microglia appeared about twice more than in the corpus callosum, but the frequency of cells per unit area was almost the same as in the corpus callosum. The microglial nucleus showed similar to that in the corplus callosum, but often with less cytoplasm around it than in the corpus callosum. The pericytal microglia numbered less than the interstitial ones and showed no significant difference from those described in the corpus callosum.

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An avascular glomerulus, measuring about 30μ in diameter, composed only of atrophic epithelial and undifferentiated mesenchymal cells was found in the kidney of a normal male rat. There were no afferent and efferent arterioles associated with this glomerulus, but a blood capillary with some juxtaglomerular cells occurred at its pole. This glomerulus was considered to be derived from a malformation in nephrogenesis and to be in the process of becoming hyalinized. Discussion was made with reference to the pathogenesis of so-called congenital glomerulosclerosis.

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Two cell lines established from human stomach cancers were used in this experiment. After culture by the coverslip method, cells were fixed and coated with carbon and gold to be observed under the scanning electron microscope.
1. When the cells began to grow in a monolayer after the subculture, the boundaries between interphasic cells were indistinguishable. The nuclei in the interphasic cells were thinner than the surrounding cytoplasm and appeared concave. However, the nucleoli were prominent in the surrounding karyoplasm and appeared convex.
2. The cell which entered the mitotic stage rose spherically among the flat interphasic cells and stretched out many fine cytoplasmic processes (0.6μ thick) in all directions.
3. In the telophase, two daughter cells were connected with a bundle of many fine cytoplasmic processes.
4. In general, the mitotic cell surface was covered with a fine granular structure which was different in appearance from a microvilli-like structure. This structure is supposed to be due to the bubbling of mitotic cells observed by time lapse cinematography.

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The ciliary ganglion of the guinea pig was studied by fluorescence and electron microscopy.
The fine structure of the perikaryon of the ganglion cells is similar to that previously described for sympathetic ganglion cells in various species of mammals.
Every presynaptic nerve ending in the ciliary ganglion contains numerous agranular vesicles mixed with a few large granular vesicles, thus corresponding to the type which has been generally considered to be cholinergic. Adrenergic nerve endings and catecholamine containing cells could not be found in the present study. No adrenergic nerve elements could be recognized even after the administration of nialamide or nialamide plus L-dopa.
These findings indicate that the ciliary ganglion cells of the guinea pig are innervated purely by cholinergic nerves. Adrenergic nerve elements do not seem to be involved in the synaptic transmission.
The spinous protrusions emerging from the postsynaptic element do not intrude into the swollen nerve endings but only cover their surface.

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The developing thyroid gland of Rana japonica Guenther during normal metamorphosis was studied with the electron microscope. The major ultrastructural changes of the thyroid gland in metamorphosing tadpoles are sequentially classified into three periods: premetamorphosis, prometamorphosis and climax metamorphosis.
In premetamorphosis the thyroid anlage is recognized as a solid mass consisting of immature cells with many pigment granules, yolk droplets and lipid droplets. Sometimes a primitive follicle lumen is encountered between two adjacent cells. There are many lysosomes in the cytoplasm. They might digest pigment granules that exist abundantly in early stages, because most of pigment granules react positively to the acid phosphatase test. Midway during this period, the follicle tissue unit is formed and the intracellular components such as the rough endoplasmic reticulum and the Golgi apparatus develop rapidly in late premetamorphosis. During prometamorphosis the follicular cell is characterized by well developed rough endoplasmic riticulum and Golgi complex, and many secretory granules are packed in the apical cytoplasm. In the climax metamorphosis a number of dense droplets, most of which react positive for acid phosphatase, are characteristic. This fact suggests that these droplets might be lysosomes to produce the thyroid hormone. This period seems to correspond to the climax in the secretion of the hormone.

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The pars distalis of normal, adrenalectomized, metopirone-administrated and sham-operated frogs was observed with the electron microscope. Based on the size, shape and internal structure of secretory granules and on the ultrastructural characteristics, seven cell types are classified.
Type 1 is a large spherical or oval cell containing spherical secretory granules, 600-1, 200mμ in diameter. Type 2 is a spherical or oval cell containing spherical secretory granules, 400-600mμ in diameter. Type 3 is a polygonal cell containing a few spherical secretory granules, some of which are cored granules, 200-350mμ in diameter. This type cell is less numerous than the others. Type 4 is an oval or cylindrical cell containing spherical secretory granules, 150-250mμ in diameter. Type 5 is a large spherical or oval cell containing spherical and rod-shaped secretory granules, 300-1, 200×300-600mμ in long and short diameters. The spherical granules are similar to those in the type 1 cell. Type 6 is an oval or cylindrical cell containing spherical and rod-shaped secretory granules, 300-400×100-300mμ in long and short diameters. The spherical granules are similar to those in the type 2 cell. Type 7 is a stellate cell without any secretory granules. Many cytoplasmic processes extend to the blood capillary.
After bilateral adrenalectomy, the type 3 cell shows marked changes in its cytoplasm. The secretory granules are extremely decreased in number, and the rough-surfaced endoplasmic reticulum and the Golgi apparatus become well developed. New granular formation is frequently found in the Golgi area. After the administration of an adrenocortical inhibitor, metopirone, similar fine structural changes are recognized in type 3 cells. These findings suggest that the type 3 cell of the frog pars distalis may secrete adrenocorticotrophic hormone (ACTH).

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