Archivum histologicum Japonicum = Nihon soshikigaku kiroku最新文献

Three-dimensional images of the microvascular architecture in the thyroid glands of levothyroxine sodium-treated (for 4 weeks) rats were examined by scanning electron microscopy of corrosion casts made by the injection of methacrylate resin. In the experimental animals, each follicle was surrounded by a clearly defined basket-like capillary network generally independent of the adjacent one in the same manner as in normal animals. However, the capillaries were markedly poor in distribution, conspicuously small in diameter, and their anastomoses were clearly decreased as compared with the normal state. The diameters of the capillaries were 3-8 microns in these cases, while those in normal specimens were 5-15 microns. The capillary bed surrounding each follicle occupied about 25% of the follicular surface area, while that in normal cases occupied about 50%. In conclusion, it became clear that the distribution and morphology of the thyroid capillaries are markedly affected and changed by the functional state of the gland.

A three-dimensional observation of the Ito cells in the rat liver was made by scanning electron microscopy (SEM) with an NaOH maceration method. The treatment with NaOH facilitated the intercellular separation of the specimen and completely removed reticular fibers around the sinusoid. In this way, the entire shapes of the Ito cells located in the perisinusoidal spaces or between the hepatocytes, were exposed under the SEM. The Ito cells were disposed at regular intervals of 30-55 microns all over the hepatic lobule, and surrounded the whole sinusoid with their subendothelial processes. SEM revealed a pattern of branching for the primary processes into secondary and tertiary processes. Furthermore, previously unknown thorn-like processes of the fourth order were also demonstrated. The Ito cells showed sparse microvilli on their surfaces confronting the hepatocytes, and occasional round elevations, these probably corresponding to lipid droplets. SEM also exhibited the relationship between the Ito cells and other types of cells in the liver. The Kupffer cells often interposed between the sinusoidal wall and the subendothelial processes of the Ito cells.

Various cells from the monocyte-macrophage line, a few neutrophils and some lymphocytes were found in the non-myelinated white matter of Jimpy mice, though there was no vascular injury to the brain parenchyma. Some of the lymphocytes appearing in the white matter were in close contact with macrophages, and occasionally with young oligodendrocytes. Such lymphocytes were mainly of the small type with few cell organelles in a scanty cytoplasm, though a few were of the medium type with a moderate amount of cell organelles in an enriched cytoplasm. Macrophages in the non-myelinated white matter displayed a highly heterogeneous cytoplasm. In particular, "cytoplasmic compartments" in macrophages displayed specific structures differing from the inclusion bodies generally seen in phagocytic cells. The contents of such "cytoplasmic compartments" were rather similar to parts of the macrophage's own cytoplasm, though they were isolated from the cytoplasm by a membrane and gaps. Our findings would seem to support the previous presumption that inherited myelin deficiency in Jimpy mice is induced by a T-cell mediated autoimmune response.

Structural changes in the ovaries of WBB6F1-Sl/Slt mutant mice aged 10, 25, 35, and 60 days and 7 months were studied light and electron microscopically. Neither secondary nor Graafian follicles could be found in any of the animals studied, and only primary follicles were usually seen until 35 days. In most follicles, the oocyte was lost. The hyperplastic proliferation of follicle epithelial cells, forming large round or oval cell clusters, occurred in 60-day-old mice. In 7-month-old animals, the ovaries were mostly occupied with invasive peritoneal epithelial tubules and masses of epitheloid cells which are apparently derived from the follicle epithelial cells. Although the ultrastructure of the oocyte and the follicle epithelial cell of the primary follicle is not different from that of +/+ control animals, the lack of gap junctions between the oocytes and the surrounding follicle epithelial cells may cause these abnormalities. The epitheloid cells that appeared in the 60-day-old animals are suggested to produce some steroid hormones, since they have cell organelles characteristic for steroid biosynthesis, such as well-developed smooth endoplasmic reticulum, oval mitochondria with tubulovesicular cristae, and numerous lipid droplets.

The islet cells and nerves in the pancreas of the ratfish Chimaera monstrosa were examined immunocytochemically by using antisera against mammalian brain-gut peptides. Five types of islet cells were recognized. The B and D cells reacted to anti-insulin and anti-somatostatin sera, respectively. The A and X cells exhibited glucagon-like immunoreactivities. The N-terminal anti-glucagon serum reacted both to the A and the X cells, while the C-terminal anti-glucagon serum bound specifically to the X cells. These results suggested that the X cells contained pancreatic-type glucagon, whereas the A cells, an enteroglucagon (glicentin)-like substance. A fifth type of endocrine cell was scattered in the islets and contained serotonin-like immunoreactivity. Two kinds of peptide nerves were identified. Vasoactive intestinal polypeptide (VIP)-immunoreactive neuronal somata were located in the intrapancreatic ganglia. Nerve fibers and terminals containing VIP-like immunoreactivities occurred in the pericapillary space surrounding the islets. Gastrin releasing peptide (GRP)-immunoreactive nerve somata and fibers were scattered along the margins of the islets. The pericapillary arrangement of these nerve terminals suggests a hemocrine release of the peptides.

The pacemaker, Purkinje system and myocardium of the sheep heart were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In the case of SEM, the heart tissues were subjected to chemical digestion procedures. The nodal cells in both the sinoatrial (SA) node and atrioventricular (AV) node were small in size and contained few nexuses with poor sarcoplasmic reticulum and myofibrillar development. These nodal cells were spindle-shaped and their ends often showed ramifications. In addition, the strands of nodal cells in the central part of the AV node were considerably compact and connected with neighboring strands to form a complicated three dimensional architecture. The muscle cells in the common bundle and Purkinje system were cuboidal or oval in shape and were broader and shorter than the working cardiac muscle cells. They had abundant nexuses, but exhibited poor sarcoplasmic reticulum and myofibrillar development. Three-dimensionally, the Purkinje strands formed a delicate network resembling a fishing-net. The atrial and ventricular myocardium consisted of long cylindrical muscle cells which often bifurcated and connected with neighboring cells. These cells had abundant nexuses, rich sarcoplasmic reticulum and well-developed myofibrils. This report discusses such morphological findings in correlation with their physiological properties.

The histogenesis of the mouse jejunal mucosa and distribution of cells capable of proliferation were studied by scanning and transmission electron microscopy and light microscopic autoradiography using 3H-thymidine. Villous primordia were found to commence their development as mucosal ridges on day 15 of gestation. Individual villi are identifiable on day 16 of gestation. Some villi reach their adult height in the neonate, while the rest gradually become longer during postnatal development. Epithelial cells lining the entire mucosal surface are undifferentiated and proliferative by day 15 of gestation. On day 16 of gestation, cells lose their proliferative capability at the upper part of the high villi, while cells lining the lower part of the villi and intervillous region remain undifferentiated as well as proliferative. As the crypt develops during postnatal development, undifferentiated proliferative cells are restricted in it, coming to reside in the lower two thirds of the crypt by day 28. The fine structural differentiation of absorptive cells starts at the upper part of villi on day 16 of gestation. The apical tubular system develops during the perinatal period. Large vacuoles, many lysosomes and lipid globules appear in suckling mice. The cells show the typical morphology of the absorptive cells by postnatal day 21. Undifferentiated proliferative cells show only little change during development: cytoplasmic organelles increase slightly and small apical granules appear during postnatal development.

Panoramic and conventional electron microscopic examinations were conducted on the mouse gastric mucosa with special reference to the distribution of immature forms of chief and parietal cells. Immature chief cells were occasionally present as high as the transitional region between the isthmus and neck of the gland, although their main localization was at the uppermost part of the base. Immature parietal cells were found in the lower part of the isthmus and throughout the neck. Cells at the same stage of maturation were often present side by side. Some cells in the neck, showing the characteristic morphology of immature parietal cells, also contained mucous granules resembling those in the mucous neck cells (intermediate cell). These findings suggest that: a chief cell may be formed by direct differentiation from the stem cell in the isthmus as well as by possible maturation of the mucous neck cell and mitotic division of the immature chief cell itself; and a parietal cell can be formed in the lower part of the isthmus and throughout the neck by direct differentiation from the stem cell or by mitotic division of the cell already determined to be a parietal cell as well as maturation of the intermediate cell.

In order to research the influences of the somites or their derivatives on the migration and differentiation of neural crest cells, unilateral extirpation of somites was performed in the larvae of the salamander (Hynobius lichenatus Boulenger). Two types of neural crest cells appeared in the somite-free environment. They could already be distinguished from each other shortly after beginning of migration. One type of the cells was distributed in the expanded space between the epidermis and the neural tube, with melanocytes differentiated from them. The other type of the cells migrated closely to the lateral wall of the neural tube. They aggregated as a cord on the ventrolateral side of the neural tube and gave rise either to neurons or to satellite cells of spinal ganglia. The sequence of cytological events along the development of the cells and the time required for each event were essentially identical with those of the melanocytes and spinal ganglion cells developing on the control side. The present results suggest not only that migration and differentiation of neural crest cells are independent of the possible regulation of the somites or their derivatives but also that the fate of neural crest cells is determined before the onset of migration.