Electron microscopic study of condylar cartilage of rat mandible stained with ruthenium red: proteoglycans and hypertrophic chondrocytes

Ultrastructure of hypertrophic chondrocytes and extracellular matrix in condylar cartilage of rat mandible was studied in conjunction with ruthenium red staining. Special care was given to the preservation of proteoglycans in the extracellular matrix. Ruthenium red-positive granules were observed in the pericellular matrix of condylar chondrocytes, and their size and number increased around the hypertrophic cells. However, these granules disappeared in the lowest hypertrophic zone, in which uncalcified cartilage matrix was also disintegrated prior to initiation of ossification. Moreover, hypertrophic chondrocytes observed at the lowest zone appeared intact in their ultrastructural features, i.e., containing numbers of lysosomes and coated vesicles in the cytoplasm facing the blood capillaries. The results strongly suggest that the lowest hypertrophic chondrocytes in rat condylar cartilage may have an active role in the degradation and resorption of the pericellular matrix, especially proteoglycans, and uncalcified matrix, which changes seem an essential step for the initiation of endochondral ossification.     

Electron microscopic observations of young rat liver

Summary Electron microscopic observations on normal liver tissue of four-day-old rats reveal the presence of numerous lamellar structures (lamellar bodies). These can be contained within parenchymal cells or in bile canaliculi, Disse's space, and in the lumen of blood sinusoids. Such bodies can also be found in Kupffer and endothelial cells.The lamellar bodies within hepatic cells are generally seen in very intimate relation to glycogen particles and lipide droplets, but in some to agranular endoplasmic reticulum and Golgi membranes as well.On the basis of this intimate relation to intracellular glycogen granules and lipide droplets, it is presumed that lamellar bodies represent a special intermediate stage in carbohydrate and lipide metabolism.Discontinuities in the endothelial layer of intrahepatic sinusoids are described.This work was supported in part by a N.A.T.O. research fellowship of the Consiglio Nazionale delle Ricerche, Roma.Assistant Professor in the Department of Veterinary Anatomy, Histology and Embryology (Dir.: Prof. A. de Girolamo), University of Naples, Naples, Italy.     

Electron microscopic observations on the renal caliceal wall in the rat

Summary The fine structure of the rat caliceal wall at its attachment to the renal parenchyma is described. Particular attention is paid to the smooth muscle cells and their associated nerves. A single overlapping layer of epithelial cells lines the renal papilla which changes abruptly to a layer of 3–5 cells where the calix gains attachment to the renal substance. In this region there is an associated increase in the underlying connective tissue which contains smooth muscle cells. These cells possess filaments, are surrounded by a basal lamina, and occur scattered among large bundles of collagen fibres. The muscle cells possess numerous branching processes as well as shorter projections which make close contacts with adjacent cells. Large numbers of axons and their associated Schwann cells are also observed in this region. The axons possess swellings, some of which lie within 800 Å of smooth muscle cells, and contain large and small granulated vesicles and agranular vesicles. They are therefore considered to be adrenergic effectors.Further out in the caliceal wall typical spindle-shaped smooth muscle cells are observed lying parallel to one another to form closely packes bundles and are associated with relatively few nerves.The significance of these observations is discussed.     

Electron microscopic observations on the mitochondrial adenosinetriphosphatase in the rat spinal cord

Summary Nucleosidetriphosphatase activity of the rat spinal cord was studied with a modified Wachstein-Meisel method at ultrastructural level. A short formaldehyde perfusion fixation favoured the preservation of the mitochondrial activity.The reaction product was localized intramitochondrially in the neuropil, while the pericaryonal mitochondria were nonreactive. Similar results were obtained, when ITP was substituted for ATP. No membrane activity was observed by Mg⁺⁺ activation only, but a certain membrane affinity was noticed in the neuropil, when Na⁺ and K⁺ were included.The specificity of the ATPase reaction reported in this paper is further discussed.Abbreviations used ATP adenosinetriphosphate - ATPase adenosinetriphosphatase - IDP inosinediphosphate - ITP inosinetriphosphate - TPP thiaminepyrophosphate - UDP uridinediphosphate     

Electron microscopic observations on the effect of gossypol on rat cauda epididymis

Gossypol administered orally to male rats at a daily dose of 20 mg/kg body weight for 63 days caused hypertrophy of the cauda epididymal epithelium, with more than fourfold increase in height of the cells. The principal cells lost most of their microvilli and formed apical blebs which appeared to produce the dense secretory material which was found in the lumen. Less dramatic but similar changes also occurred after 9 days on the same regimen, with the height of the epithelium doubling. However after 19 days on this regimen, with the height of the epithelium doubling. However after 19 days on this regimen, the epithelium looked fairly normal apart from a maintained hypertrophy. As reported in other studies, the cauda epididymal sperm were severely damaged and immotile; many were decapitated and the oxygen uptake was low. Ultrastructural defects were abnormal or absent mitochondria, absence of plasma membranes and axonemal components and accessory fibres.     

椰毒假单脆菌的电镜观察

A strain of food-poisoning bacterium has been isolated by Jin Jiexiang (1963) in China from the fermented cornflour that has gone bad. These pathogenic microorganism has been identified and named Pseudomonas by Zhao Naixin in 1988, which is the same species as P. cocovenenans. The characteristics of them were conformed to these of the species P. cepacia of section 2 of the genus Pseudomonas. In view of the fact that the fine structures of the above mentioned three strains of Pseudomonas have not been described yet, we decided to observe them with electron microscope. Results indicate there are many things in common among the three strains, such as: appearing short rods, 0.6-0.8 microns in diameter by 1.5-2.0 microns in length, one polar multiflagella; non-pili, non-capsules, non-endospores; containing intranuclear inclusions (electron-dense bodies or concentric laminae bodies), accumulating intracytoplasmic PHB granules; forming filaments, minicells and bizarrecells; producing extracellular cellulose-like materials by the three strains have not been reported previously.     

The fate of Meckel's cartilage chondrocytes in ocular culture

Modulation of the chondrocyte phenotype was observed in an organ culture system using Meckel's cartilage. First branchial arch cartilage was dissected from fetal rats of 16- and 17-day gestation. Perichondrium was mechanically removed, cartilage was split at the rostral process, and each half was grafted into the anterior chamber of an adult rat eye. The observed pattern of development in nonirradiated specimens was the following: hypertrophy of the rostral process and endochondral-type ossification, fibrous atrophy in the midsection, and mineralization of the malleus and incus. A change in matrix composition of the implanted cartilage was demonstrated with immunofluorescence staining for cartilage-specific proteoglycan (CSPG). After 15 days of culture, CSPG was found in the auricular process but not in the midsection or rostral process. In order to mark the implanted cells and follow their fate, cartilage was labeled in vitro with [3H]thymidine [3H]TdR). Immediately after labeling 20% of the chondrocytes contained [3H]TdR. After culturing for 5 days, 20% of the chondrocytes were still labeled and 10% of the osteogenic cells also contained radioactive label. The labeling index decreased in both cell types with increased duration of culture. Multinucleated clast-type cells did not contain label. Additional cartilages not labeled with [3H]TdR were exposed to between 20000 and 6000 rad of gamma irradiation before ocular implantation. Irradiated cartilage did not hypertrophy or form bone but a fibrous region developed in the midsection. Cells of the host animal were not induced to form bone around the irradiated cartilage. Our studies suggest that fully differentiated chondrocytes of Meckel's cartilage have the capacity to become osteocytes, osteoblasts, and fibroblasts.     

多形类杆菌的电镜观察

Three strains of B. thetaiotaomicron have been isolated from caeca of BALB/c-nu/+ mice of SPF. These Bacteroides are obligately anaerobic, Gram-negative, non-spore-forming and non-motil without flagella rods. A characteristic of staining is deep at ends and stainless at the medium of a rod. The isolation and identification of these strains has been reported in 1987. This paper introduced only the results of EM observations. Under the SEM, the unstained area of rods is always showing a concavity, which is just a nucleoid in sections under the TEM. Many lamellar corpuscles have been found in cell plasma. Some of them have been secreted out of the cells. The chemical properties and physiological functions of them are unknown.     

Effects of mechanical loads on surface morphology of the condylar cartilage of the mandible in rats

Mechanical loads on the condylar cartilage were varied by feeding either a hard diet, a soft diet, or a sequential combination of a soft diet followed by a hard diet to young male and female rats for a total period of 4 weeks, and to mature male rats for 12 weeks. Gross condylar dimensions were greatest in the hard-diet groups, intermediate in the combination soft/hard-diet groups, and smallest in the soft-diet groups. Scanning electron microscopy of the condyle revealed a smooth, nonporous articular surface in the soft-diet groups. Hard-diet condyles had a rougher, more porous articular surface while soft/hard-diet condyles were intermediate between nonporous and slightly roughened condyles. None of the condyles showed ridges or elevations on the articular surface. Sex, age and time of the diets did not significantly affect these results.     

Electron microscopic studies on guinea pig rib cartilage

Summary The guinea-pig rib cartilage consists of chondrocytes dispersed in an intercellular substance composed of collagen fibrils, often characteristically cross-striated, and polygonal granules. Electron-dense membrane-bounded matrix vesicles are also observed intercellularly, especially in the central, partly calcified zone of the cartilage. With respect to their location in a cross-section of the rib, the chondrocytes differ in size, shape and intracellular fine structure. Thus, three separate types of cells are recognized. Peripheral chondrocytes have a flattened shape and are largely occupied by the nucleus. In the cytoplasm, the granular endoplasmic reticulum is the most extensive organelle. Intermediate chondrocytes are oval or round in shape. The endoplasmic reticulum and the Golgi complex are both prominent. Mitochondria and membrane-bounded cytoplasmic dense bodies are more numerous than in the peripheral cells. The ground cytoplasm often contains a few lipid droplets. In the central chondrocytes, such droplets sometimes fill the entire cytoplasm. Concomitantly, the nucleus is usually completely heterochromatic and the cells are therefore regarded as being metabolically inert.After preparations including ruthenium red staining en bloc, the general stainability of the chondrocytes is decreased. Intracellularly, positive ruthenium red staining of granular material within the Golgi vacuoles are to be observed. Extracellularly, the matrix granules are stained with this polyvalent, cationic dye. Extraction of the cartilage with 4 M guanidine-HCl removes all matrix granules and about 70% of the proteoglycans, measured as hexosamine, from the tissue. It is concluded that the matrix granules contain proteoglycan complexes.Financial support was received from the Swedish Medical Research Council (proj. no. 12X-3355), the Swedish Cancer Society (proj. no. 100-K71-05XK), the King Gustaf V 80th Birthday Fund, the Harald and Greta Jeansson Foundation, the C. B. Nathhorst Foundation, and from the funds of Karolinska Institutet.The skilled technical assistance of Mrs. Eva Lundberg and the secretarial assistance of Mrs. Inger Åhrén are gratefully acknowledged. The authors are indebted to Dr. S. Lohmander for helpful suggestions during the progress of the work.     

Electron microscopic observations on extraneuronal lipofuscin in the monkey brain

Protein synthesizing activity of the rat hypothalamic arcuate nucleus following partial or total deafferentation of the medial basal hypothalamus was studied by light and electron microscopic autoradiography when administering tritiated leucine into the lateral ventricle. There were significantly more grains over the arcuate nucleus 21 days after disconnection of this hypothalamic region than over the intact nucleus. Isolation of a temporal cortical region induced similar changes in the isolated area, although this effect was not so pronounced as in the arcuate region. Data suggest that the protein synthesizing activity of arcuate neurons increases significantly after interruption of neural connections of the medial basal hypothalamus. It is assumed that the effect is primarily due to transneuronal alteration and/or interruption of inhibitory afferents.     

The fate of chondrocytes during ageing of human thyroid cartilage

Human laryngeal cartilages, especially thyroid cartilage, exhibit gender-specific ageing. In contrast to male thyroid cartilages, the ventral half of the female thyroid cartilage plate remains unmineralized until advanced age. In cartilage specimens from laryngectomies and autopsies, apoptosis was studied immunohistochemically and the oxidative mitochondrial enzyme nicotinamide adenine dinucleotide hydride tetrazolium reductase (NADH-TR) was localized histochemically. In addition, very fresh specimens from laryngectomies were fixed under addition of ruthenium hexamine trichloride or tannin to fixation solution to study cell organelles of chondrocytes by electron microscopic methods. In general, apoptotic chondrocytes decreased in thyroid cartilages of both genders, especially after the second decade. In the age group 41–60 years, thyroid cartilage from male specimens revealed a significantly higher percentage of apoptotic cells than did thyroid cartilage from women (P = 0.004), whereas in the age groups 0–20 years and 61–79 years no statistically significant gender difference was determined. In general, thyroid cartilage from women contained more living chondrocytes into advanced age than men. Chondrocytes adjacent to mineralized cartilage were partly positive for apoptosis and NADH-TR and partly negative. Apoptotic chondrocytes often were localized in areas of asbestoid fibres where vascularization and mineralization took place first. Electron microscopy revealed remnants of chondrocytes in asbestoid fibres. Taken together, it can be assumed that some chondrocytes in thyroid cartilage die by apoptosis and that these chondrocytes are characterized by absent reactivity for the mitochondrial enzyme NADH-TR. A possible influence of sexual hormones on apoptotic death of thyroid cartilage cells requires further elucidation.