Takuro Ogata

Ultra-high-resolution scanning electron microscopy of mitochondria and sarcoplasmic reticulum arrangement in human red, white, and intermediate muscle fibers.

ABSTRACT Background: Human skeletal muscle fibers are the red, white, and intermediate fibers. They differ in their mitochondrial structure and enzyme activity. Scanning electron microscopy (SEM) was used on specially prepared specimens to determine the distinctive features of mitochondria and sarcoplasmic reticulum (SR) in each fiber type.

Scanning electron-microscopic studies on the three-dimensional structure of mitochondria in the mammalian red, white and intermediate muscle fibers

SummaryThe three-dimensional structure and arrangement of mitochondria in the red, white and intermediate striated muscle fibers of the rat were examined under a field-emission type scanning electron microscope after removal of cytoplasmic matrices by means of the Osmium-DMSO-Osmium procedure.Beneath the sarcolemma, spherical or ovoid subsarcolemmal mitochondria show accumulations. The mitochondria are numerous and large in size in the red fibers, intermediate in the intermediate fibers, and few and small in the white fibers. Paired, slender I-band-limited mitochondria were located on both sides of the Z-line and partly embraced the myofibrils at the I-band level; they occurred in all three types of fibers. In the intermyofibrillar spaces, numerous mitochondria formed mitochondrial columns. These columns were classified into two types: 1) thick mitochondrial columns, formed by multiple mitochondria each with an intermyofibrillar space corresponding to one sarcomere in length, and 2) thin mitochondrial columns, established by single mitochondria corresponding to one sarcomere in length. In the red fibers mitochondrial columns were abundant and the ratio of the thick and thin columns was almost the same, while in the intermediate fibers most of the columns belonged to the thin type. The white fibers displayed rare, very thin columns.

A morphological study on the histogenesis of human colorectal hyperplastic polyps.

Abstract Background & Aims Little is known about the histogenesis of human colorectal hyperplastic polyp, although this polyp is clinically very common. Therefore, the structural features of the polyp and their implications regarding histogenesis were studied. Methods A total of 261 foci were examined using scanning electron-microscopic observation of the isolated crypt and surface structure, NaOH cell maceration and scanning electron microscopy, dissecting microscopy, and standard histological analysis. Results In surface view, each polyp crypt was discretely demarcated as in the normal crypt, suggesting that the crypt epithelium had not replaced the adjoining crypt. Notches at the base and various stages of branching, observed in 21.8% of the isolated crypts, were considered to reflect crypt fission. Several polyps with a single crypt mouth consisting of fissioned multiple crypts suggested polyp origin from a single crypt and growth by fission. Juxtaposition of small polyps and their fusion suggested polycentric origin. Almost all polyps showed increased stromal inflammatory cell infiltration and/or a lymphoid follicle at the base. Conclusions Hyperplastic polyps originate by the apparent fusion of single abnormal crypts within a small region of mucosa. The polyps grow by fission of the crypt and fusion of the polycentrically originated polyps. Chronic inflammation has some relation to this process.

A 10-year experience of intraoperative radiotherapy for gastric carcinoma and a new surgical method of creating a wider irradiation field for cases of total gastrectomy patients

PURPOSE To improve the prognosis of gastric cancer, radical surgical resection with extensive lymph node dissection plus intraoperative radiation therapy (IORT) was tried in our clinic. In addition, a new operative procedure was created to obtain wider irradiation field for total gastrectomy patients. METHODS AND MATERIALS A total of 183 gastric cancer patients who underwent radical gastrectomy with or without IORT from August 1983 to July 1992 were retrospectively evaluated. The patients were divided into two groups: group 1 consisted of 58 patients who underwent radical operation plus IORT. A single dose of 28 to 30 Gy was delivered around the celiac axis with an electron beam of 12 MeV. Group 2, our historical control group, which showed no difference in age, sex and stage, consisted of 120 patients who underwent only radical surgery. In addition, a new method of total gastrectomy with IORT after mobilization of the tail and body of the pancreas was devised to get wider irradiation field for advanced gastric cancer. RESULTS Of the Stage II gastric cancer patients, all the 11 patients of group 1 are alive, whereas in group 2, the 4-year and the 8-year survival rates were 60% and 48%, respectively. In Stage III patients, the 8-year survival rate of group 1 was 55% vs. 35% in group 2. As for Stage IV patients, the 5-year survival rate of group 1 was 12% and that of group 2 was 13%. CONCLUSION Using this combined treatment modality of radical surgical operation+IORT, improved survival rates were obtained for Stage II and III gastric cancer patients. However, the method was ineffective for more advanced, Stage IV, patients. The wider irradiation field method used for total gastrectomy patients was safe and no complications were encountered.

Ultra-high-resolution scanning electron microscopy of the sarcoplasmic reticulum of the rat atrial myocardial cells.

The sarcoplasmic reticulum (SR) of mammalian ventricular and atrial muscles share common features but also differ because T‐tubules are rare and extended junctional SR is exclusively seen in the atrium. This scanning electron microscope (SEM) study was undertaken to clarify the three‐dimensional organization of the rat atrial SR system. Specific preparations were examined with an ultra‐high‐resolution SEM.

Scanning electron-microscopic studies on the three-dimensional structure of sarcoplasmic reticulum in the mammalian red, white and intermediate muscle fibers

SummaryThe three-dimensional structure of the sarcoplasmic reticulum (SR) in the red, white and intermediate striated muscle fibers of the extensor digitorum longus muscle of the rat was examined under a field-emission type scanning electron microscope after removal of cytoplasmic matrices by the osmium-DMSO-osmium procedure.In all three types of fibers, the terminal cisternae and transverse tubules form triads at the level of the A-I junction. Numerous slender sarcotubules, originating from the A-band side terminal cisternae, extend obliquely or longitudinally and form oval or irregular shaped networks of various sizes in front of the A-band, then become continuous with the tiny mesh (fenestrated collar) in front of the H-band. The A-and H-band SR appears as a single sheet of anastomotic tubules. Numerous sarcotubules, originating from the I-band side terminal cisternae, extend in threedimensional directions and form a multilayered network over the I-band and Z-line regions. At the I-band level, paired transversely oriented mitochondria partly embrace the myofibril. The I-band SR network is poorly developed in the narrow space between the paired mitochondria, but is well developed in places devoid of these mitochondria.The three-dimensional structure of the SR is basically the same in all three muscle fiber-types. However, the SR is sparse on the surface of mitochondria, so the mitochondria-rich red fiber has a much smaller total volume of SR than the mitochondria-poor white fiber. Moreover, the volume of SR of the intermediate fiber is intermediate between the two.

High -resolution scanning electron-microscopic studies on the three-dimensional structure of mitochondria and sarcoplasmic reticulum in the different twitch muscle fibers of the frog

SummaryThe three-dimensional structure of the mitochondria and sarcoplasmic reticulum (SR) in the three types of twitch fibers, i.e., the red, white and intermediate skeletal muscle fibers, of the vastus lateralis muscle of the Japanese meadow frog (Rana nigromaculata nigromaculata Hallowell) was examined by high resolution scanning electron microscopy, after removal of the cytoplasmic matrices.The small red fibers have numerous mitochondrial columns of large diameter, while the large white fibers have a small number of mitochondrial columns of small diameter. In the medium-size intermediate fibers, the number and diameter of the mitochondrial columns are intermediate between those of the red and white fibers.In all three types of fibers, the terminal cisternae and transverse tubules form triads at the level of each Z-line. The thick terminal cisternae continue into much thinner flat intermediate cisternae, through a transitional part where a row of tiny indentations can be observed. Numerous slender longitudinal tubules originating from the intermediate cisternae, extend longitudinally or obliquely and form elongated oval networks of various sizes in front of the A-band, then fuse to form the H-band collar (fenestrated collar) around the myofibrils. On the surface of the H-band collar, small fenestrations as well as tiny hollows are seen. The three-dimensional structure of SR is basically the same in all three muscle fiber-types. However, the SR is sparse on the surface of mitochondria, so the mitochondria-rich red fiber has a smaller total volume of SR than the mitochondria-poor white fiber. The volume of SR of the intermediate fiber is intermediate between other the two.

HISTOCHEMICAL STUDY OF OXIDATIVE ENZYMES IN INVERTEBRATE MUSCLES

A histochemical study of oxidative enzymes was carried out on various kinds of invertebrate muscles and the results obtained were as follows: 1. Insect flight muscles showed the presence of the most intense activity of succinic dehydrogenase and high activity of α-glycerophosphate and glutamic dehydrogenases. 2. Regarding crustacean striated muscles, prawn muscle was distinguished into types of fibers by oxidative enzyme reactions. 3. In molluscan muscles, the squid and octopus muscle fibers were distinguished into two types by their oxidative enzyme activities. 4. The earthworm body wall muscle was made of only one type of fibers, whose oxidative enzyme activities were low.

Morphological studies on the translocation of tubulovesicular system toward the intracellular canaliculus during stimulation of the gastric parietal cell

The gastric parietal has two characteristic membrane systems. One is the intracellular canaliculus, which is specialized networks of enfolded luminal membrane channels lined with numerous microvilli. The other structures common to all parietal cells are the tubulovesicles or the tubulovesicular membranes, a system of tubules and vesicles. The tubulovesicular compartment is drastically depleted during maximal gastric acid secretion and this is coincident with an increase in the canalicular cell surface membrane. A plausible explanation for this redistribution is the fusion and transfer of tubulovesicular membranes to the plasma membrane. However, for many years there was no convincing evidence of connections between these two membrane systems. The mechanism of the transformation of tubulovesicular membrane into the plasma membrane without demonstrable connections has been an enigma to electron microscopists. Using a recently developed fixation technique for parietal cells [Sugai et al. ( 1995 ) Acta Anat Nippon 74:S101], we have investigated the organization of the cytoplasmic membrane systems in the rat resting and tetragastrin stimulated stomachs by ultra‐high‐resolution scanning electron microscopy (SEM). Gastric mucosae were microwave‐fixed in a cacodylate buffer, (334 milliosmoles/kgH2O (mOsm)), to which 1.0% glutaraldehyde and 0.5% formaldehyde were added. Specimens examined by TEM of thin sections revealed the cytoplasm packed with tubular membranes similar to images detected by rapid‐freeze/freeze‐substitution fixation. To render the cytoplasmic membranes visible by SEM, fixed mucosae were treated by the aldehyde‐osmium‐DMSO‐osmium maceration procedure. With much of the cell matrix and filaments removed, SEM revealed numerous 30–60‐nm tubules, which formed a meshwork with small cisternae. Vesicles or isolated tubules were not found in adequately macerated parietal cells. The cytoplasmic surface of the intracellular canaliculus was smooth except for round openings representing the bases of macerated microvilli. In favorable sites, connections of the tubular membranes to the canaliculi were clearly visible. Stereo pair views were particularly useful to demonstrate these continuities. Connections between these two membrane compartments suggest the probability of rapid membrane transposition. In this article, the form and distribution of membrane systems of parietal cells in the resting state and after tetragastrin stimulation will be presented and discussed. Special emphasis is made to demonstrate connections between the tubulovesicular system and the intracellular canaliculus. Microsc. Res. Tech. 48:282–292, 2000

Scanning EM of resting gastric parietal cells reveals a network of cytoplasmic tubules and cisternae connected to the intracellular canaliculus

Using a recently developed fixation technique for parietal cells (Sugai et al., Acta Anat Nippon 1995:70:S79, 1999:74:S101), we have reinvestigated the organization of the cytoplasmic membrane system in the resting stomach by ultra‐high‐resolution scanning electron microscopy (SEM). Rat gastric mucosae were microwave‐fixed in cacodylate buffer [334 milliosmoles/kg H2O (mOsm)], to which 1.0% glutaraldehyde and 0.5% formaldehyde were added. Specimens examined by transmission electron microscopy (TEM) of thin sections revealed cytoplasm packed with tubular membranes similar to images detected by rapid‐freeze/freeze‐substitution fixation which is generally considered to cause minimal structural alterations. To render the cytoplasmic membranes visible by SEM, fixed mucosae were frozen, fractured, and the exposed cytoplasm of parietal cells was macerated by the aldehyde‐osmium‐DMSO‐osmium procedure. With much of the cell matrix and filaments removed, SEM revealed numerous 30–60 nm tubules which formed a meshwork and also small cisternae. The cytoplasmic surface of the tubules was smooth while some cisternal areas had attached polyribosomes. Vesicles or isolated tubules were not found in appropriately macerated parietal cells. The cytoplasmic surface of the intracellular canaliculus was smooth except for round openings representing the bases of macerated microvilli. In favorable sites connections of the tubular membranes to the canaliculi were clearly visible. Stereo pair views were particularly useful to demonstrate these continuities. Connections between these two membrane compartments suggest the probability of rapid membrane transposition. Anat Rec 258:15–24, 2000.