Presence of laminin B chain-like protein in bovine and rat adrenal chromaffin granules

The presence of a glycoprotein laminin in bovine adrenal chromaffin granules was examined by SDS-PAGE followed by immunoblotting. The two chromaffin granule membrane fractions were obtained by linear sucrose gradient centrifugation followed by freezing and thawing and gel-filtration of the chromaffin granule-rich fraction, respectively. The purity of the granules in these fractions was examined by electron microscopy. These fractions contained laminin B chain-like immunoreactivity as a major immunoreactive component against anti-laminin. Laminin A chain-like immunoreactive protein was undetectable. The soluble fraction of the chromaffin granules contained no immunoreactive peptide. The presence of laminin-like immunoreactivity in the chromaffin granules was confirmed by immunocytochemical study. Laminin B chain-like immunoreactivity was also identified in the rat adrenal chromaffin granule fraction. Laminin A chain was hardly detected, as in the case of bovine adrenals. Structure of laminin in chromaffin granules in bovine and rat adrenals may be different from that of mouse Englebrethe-Holm-Swarm sarcoma laminin. The functional significance of laminin B chain-like protein in the granules is unknown at present.

Autoradiographic analysis of the uptake of [3H]dopamine, [3H]angiotensin II and [3H]gamma aminobutyric acid by the chicken thrombocyte

The ability of chicken thrombocytes to take up and store transmitters of different categories, such as dopamine, angiotensin II and gamma aminobutyric acid (GABA), was examined by electron microscope autoradiography. Chicken thrombocytes selectively took up [3H]dopamine, which was stored in large vacuoles with peripherally situated electron-dense granules. Exogenous [3H]angiotensin II was also taken up by chicken thrombocytes. This accumulated in the same large vacuoles in which [3H]dopamine was stored. No active uptake of exogenous [3H]GABA was detected. The results indicate that chicken thrombocytes take up exogenous dopamine and angiotensin II which both appear to be stored in the same vacuoles, the amine storage organelles.

Electron microscopic cytochemistry on the distribution of wheat germ agglutinin receptor on the platelet plasma membrane after treatment with convulxin isolated from Crotalus durissus terrificus venom

The effects of convulxin, isolated from the venom of Crotalus durissus terrificus, on the localization and distribution of wheat germ agglutinin (WGA) binding sites on platelet surfaces have been investigated at an ultrastructural level. A post-embedding cytochemical technique using WGA-gold complexes was used and the quantitative intensity of WGA-labeling on the surface membrane of platelets after convulxin stimulation was determined. In the presence of Ca2+, convulxin induced platelet release and aggregation, while in its absence, the platelets formed pseudopodia and showed release reaction, but without aggregation. After treatment with convulxin, WGA-labeling on the surface membrane decreased compared with intact washed (control) platelets. In the presence of Ca2+, clusters of gold label were often found on the surface membrane. However, the WGA-labeling intensity of the membrane of the open canalicular system increased significantly compared with that of platelets stimulated by convulxin in the absence of Ca2+. Direct morphological evidence demonstrates qualitative and quantitative alterations of WGA-labeling on the surface membrane of platelets, after convulxin stimulation. The possibility is considered that WGA-binding glycoproteins on the surface membrane are involved in the aggregation response after convulxin stimulation.

Autoradiographic analysis of vasoactive neuropeptide uptake by rabbit megakaryocytes and platelets

Autoradiographic analysis has been performed to determine whether or not platelets and megakaryocytes can take up in vitro vasoactive neuropeptides such as [3H]angiotensin II, [3H]neuropeptide Y, [3H]substance P and [3H]vasopressin. Light microscope autoradiography has revealed the active uptake of [3H]angiotensin II by megakaryocytes. [3H]angiotensin II uptake by platelets has also been confirmed by electron microscope autoradiography. Silver grains are preferentially associated with the dense bodies of platelets. Neither megakaryocytes nor platelets show any active uptake of [3H]neuropeptide Y or [3H]substance P. Megakaryocytes are slightly labelled after incubation with [3H]vasopressin.

Microprobe analyses of the potassium-calcium distribution relationship in predentine

Apex regions of continuously growing incisors of Wistar rats were quickly dissected, shock-frozen in liquid nitrogen-cooled propane, freeze-dried at -80 degrees C and infiltrated with Spurr's resin. 400nm thick dry sections were cut with a diamond knife on an ultramicrotome. Relatively flat sections were transferred with an eye lash onto collodium coated aluminum grids. They were flattened with a glass stick and by placing another collodium coated aluminum grid just on top of the first one, exerting a uniform pressure. After carbon coating the sections were observed using the backscattered and secondary electron signals in a scanning microscope. The predentine was analyzed for calcium and potassium with an energy dispersive x-ray analysis system. The x-ray spectra revealed in the predentine regions with beginning dentine formation, near the apex, an uneven K-distribution with very low as well as more prominent x-ray peaks. The K peaks were always lower than those of calcium. In areas with advanced dentine formation, prominent K-peaks were always observed. They were normally higher than the Ca-peaks up to a distance of 5-10 microns from the dentine border. Closer to the dentine border the K concentration decreased while the Ca-peak increased. This might indicate that (besides Na) K is used to balance the negative charges of the macromolecules till K is replaced by Ca at the onset of apatite crystal formation.

Location of sites of dopamine storage in megakaryocytes by autoradiography

We have used quantitative electron microscope autoradiography to study the subcellular sites of 3H-dopamine uptake in mouse megakaryocytes after a single intraperitoneal injection. Autoradiographic grains were found to be associated almost exclusively with the vesicles of precursors of monoamine-storage organelles. The labeling intensity (radioactivity) of the demarcation membrane system which is continuous with the plasmalemma was also significantly greater than would be expected. On the other hand, radioactivity associated with the remaining sites in the cytoplasm was not significantly different from that expected of a random distribution. In order to compare 3H-dopamine uptake during cell maturation, light microscope autoradiographic studies were also done. Immature megakaryocytes were labeled slightly, but the number of silver grains increased significantly in maturing cells. Mature megakaryocytes were 2.7 times more radioactive than the maturing cells. Our results suggest that the megakaryocytes were able to accumulate dopamine from the early stages of cell maturation and to store dopamine in precursors of monoamine-storage organelles.

Alterations of wheat-germ agglutinin binding pattern on cell surface of blood platelets after thrombin stimulation

An attempt was made to demonstrate wheat-germ agglutinin (WGA) binding sites on platelet surfaces after thrombin stimulation, by means of a post-embedding cytochemical technique using colloidal gold as marker at an ultrastructural level. In unstimulated platelets washed with EDTA, an intense uniform labeling of WGA-gold complexes was found on the surface membrane. When washed platelets were stimulated by thrombin in the absence of Ca2+, only a release reaction was induced. WGA labeling on the surface membranes of these platelets decreased dramatically. However, the labeling intensity of WGA-gold complexes on the surface membrane of aggregated platelets induced by thrombin in the presence of Ca2+ increased significantly compared to that of thrombin-stimulated platelets in the absence of Ca2+. In contrast to the uniform labeling on the surface membranes of unstimulated platelets, clusters of gold label were often found on the surface membrane of the aggregated platelets, although there was no significant quantitative difference in the labeling intensity between these two groups. Thus, we present direct morphological evidence demonstrating qualitative and quantitative alterations of WGA labeling on the surface membrane of platelets after thrombin stimulation. The possibility is considered that WGA-binding glycoproteins in the surface membrane are involved in the aggregation response after thrombin stimulation.

Electron microscopic and cytochemical studies of the thrombocytes of the tortoise (Geoclemys reevesii)

The thrombocytes of the tortoise (Geoclemys reevesii) were studied at the electron microscopic level. The presence of a surface connected canalicular system, composed of numerous anastomosing canaliculi, has been demonstrated by the ruthenium red technique. However, monoamine storage organelles have not been found in tortoise thrombocytes. Peroxidase activity is localised to the nuclear envelope and the rough surfaced endoplasmic reticulum, but is not present in the Golgi apparatus or granules. Acid phosphatase is localised to the large inclusions with myelin bodies, but is not found in the electron-lucent small granules. These results are discussed in relation to those from comparable studies of mammalian and submammalian thrombocytes.

Uptake of 3H-dopamine in megakaryocytes and blood platelets measured by quantitative electron-microscope autoradiography

We studied the uptake of dopamine by mature megakaryocytes and blood platelets in mouse spleen after a single intraperitoneal injection of 3H-dopamine. In order to compare the uptake of 3H-dopamine in mature megakaryocytes and blood platelets, we used quantitative autoradiography at the electron-microscope level. Dense accumulations of silver grains were observed on both mature megakaryocytes and blood platelets; all other tissue elements of the spleen exhibited considerably less dense labeling. No significant differences with regard to dopamine uptake were observed in megakaryocytes and blood platelets. This is in contrast to the previous finding of very different patterns of 3H-5-hydroxytryptamine labeling in mature megakaryocytes and blood platelets (Daimon and Uchida 1985). The results of the present study provide new evidence in favor of the hypothesis that the active uptake mechanism of dopamine through the plasma membrane is different from the uptake mechanism of 5-hydroxytryptamine.

Ultrastructural evidence of the existence of the surface connected canalicular system in the thrombocyte of the shark (Triakis scyllia)

The existence of the surface-connected canalicular system has been demonstrated ultrastructurally in shark [Triakis scyllia) thrombocytes using the ruthenium red method to fix and stain the glycocalyx. In ultrathin sections fixed routinely in glutaraldehyde followed by osmium tetroxide, numbers of electron-lucent vesicles are distributed throughout the cytoplasm. Since ruthenium red-positive reaction product is deposited on the inner surface of these vesicles, they are defined as the surface-connected canalicular system. Moreover, the semithin sectioned thrombocytes fixed by the ruthenium red method provide evidence that the surface-connected system is not composed of vesicles but also of numerous canaliculi. These results suggest that the surface-connected canalicular system is one of the most basic organelles of the thrombocyte system, common to submammalian species and to mammals.

Ultrastructural distribution of peroxidase in thrombocytes of mammals and submammals

The localization and distribution of peroxidase (PPO) activity were studied ultracytochemically in thrombocytes from lampreys, carps, frogs, snakes, tortoises, rabbits, sheep, dogs, and monkeys. PPO activity was not detectable in the thrombocytes of lampreys, carps, frogs, and snakes. However, this enzyme activity was demonstrated in the nuclear envelope and endoplasmic reticulum of tortoise thrombocytes. Dog and monkey thrombocytes (blood platelets) exhibited PPO activity in the dense tubular system, but this enzyme activity was not detectable in rabbit and sheep thrombocytes. Our observations are interpreted to suggest that thrombocytes from animals lower than amphibia are peroxidase negative. Furthermore, it can be said that thrombocytes from animals higher than reptiles are generally positive, although there are exceptions. PPO activity was localized in the endoplasmic-reticulum system, but not in the cytoplasmic granules of thrombocytes common to submammals and mammals. In this study, we also compared the distribution of peroxidase activity in thrombocytes, neutrophils, and eosinophils and conclude that these are significant differences in the distribution of PPO and myeloperoxidase.

Morphometric study on the absolute volume of differentiating hepatocytes in rats

Quantitative changes in the mean absolute volume of rat hepatocytes during prenatal development were studied by light microscopic stereological methods. Combining these light microscopic measurements with electron microscopic relative volume (volume density) data (Daimon et al. 1982) enabled the evaluation of the mean absolute volumes of cytoplasmic organelles of fetuses and newborns. On the 15th day of gestation the mean absolute volume of hepatocytes was 1,523 +/- 10.7 microns3. After 3 days hepatocytes were enlarged 66.2% (2,531.5 +/- 108.2) and at birth 157.1% (3,915.6 +/- 190.8). The comparison of the absolute volume and the volume density of each cell organelle made possible the interpretation of much functional and morphometric data of the development of hepatocytes.

Precursors of monoamine-storage organelles in developing megakaryocytes of the rat

Identification and distribution of the precursors of amine-storage organelles in rat megakaryocytes during cell maturation were studied, using the uranaffin reaction for adenine nucleotide. The precursors of the amine-storage organelles appeared as 200-300 nm vesicles having an uranaffin electron dense granule, whereas they appeared as empty vesicles by conventional glutaraldehyde-OsO4 fixation. X-ray probe microanalysis confirmed the existence of U and P in the uranaffin reaction positive vesicles. The precursors appeared in the immature megakaryocytes, especially at the trans(mature) face of the Golgi apparatus, and rapidly increased in number in the maturing cells. The size of the uranaffin granules in the precursor organelles increased gradually during cell maturation and became almost equivalent to the dense body of blood platelets in the final stage of cell maturation.

Elemental composition of the dense bodies of rat platelets determined by electron probe x-ray microanalysis of freeze-substituted sections

A semiquantitative x-ray microanalytical study was made of dense bodies in rat and human blood platelets prepared by freeze substitution. After the freeze substitution, electron dense bodies containing 5-hydroxytryptamine(5-HT) were well preserved. Electron probe x-ray microanalyses clearly defined species differences in the cations of dense bodies of rat and man. Direct calculation of elemental concentration ratios demonstrated a high level of Mg, with lesser amounts of K and Ca in rat, while there was a negligible level of Mg in man but a high amount of Ca. These results indicate that freeze-substitution is a suitable preparation for the study of diffusible electrolytes which may open the way to quantitative analysis using appropriate standards for analytical electron microscopy of resin sections.

Cytochemical demonstration of amine-storing vacuoles and lysosomes in the chicken thrombocytes

A combined electron microscopic and cytochemical study of the thrombocytes of the chicken has clearly identified the amine-storing organelles and lysosomes. A chromaffin positive-reaction product was observed on the inner surface and the granules of the large electron-lucent vacuoles. No acid phosphatase activity was localized in these amine-storing vacuoles. However, the acid phosphatase activity was observed in the small vesicles, the primary lysosomes, and in the large electron dense inclusions with myelin which may be secondary lysosomes. The results of this study suggest that the large empty vacuoles, with one or two very dense osmiophilic peripherally-situated granules, in the chicken thrombocytes are comparable to the vesicles with electron dense materials called "dense bodies" in mammalian thrombocytes.

Intracellular calcium translocation during contraction in vertebrate and invertebrate smooth muscles as studied by the pyroantimonate method

The intracellular localization of activator Ca and its translocation during the mechanical activity were studied on vertebrate and invertebrate smooth muscles by fixing muscle fibers with a 1% OsO4 solution containing 2% potassium pyroantimonate for electron microscopic examination. When guniea-pig taenia coli, Mytilus anterior byssal retractor muscle, and Dorabella longitudinal body wall muscle were fixed during the relaxed state, electron-opaque pyroantimonate precipitate containing Ca was localized along the inner surface of the plasma membrane and at other membranous structures in close apposition to the plasma membrane, in accordance with physiological evidence that these muscles contain intracellularly stored activator Ca. When they were fixed during the contracted state, the precipitate was distributed diffusely in the myoplasm in the form of small particles, indicating the release of activator Ca from the peripheral structures. The contraction in dog coronary artery smooth muscle appears to be associated with the inward movement of extracellular Ca. In accordance with this, the resting coronary artery muscle fibers exhibited the precipitate in the lumen of the caveolae, i.e., the bottle-shaped plasma membrane investigations, but not at the peripheral intracellular structures, though the contracted fibers showed the diffuse distribution of the precipitate in the myoplasm. These results indicate that the pyroantimonate method is very effective in studying the translocation of activator Ca in various types of smooth muscles.

Correlated ultrastructural and morphometric studies on the liver during prenatal development of rats

Quantitative and qualitative changes in liver tissues during prenatal development were studied by electron microscopy and morphometry. On the 15th day, 30% of fetal liver volume consisted of hepatocytes, and the extrahepatocytic spaces amounted to 63%. The hemopoietic cells occupied 93% of the extrahepatocytic spaces. Immature bile canaliculi were observed and amounted only to 0.14% of extrahepatocytic spaces. The hepatocytes were irregular in shape and possessed several large lipid droplets which amounted to 19% of the cytoplasm. Although the rough surfaced endoplasmic reticulum (RER) was well developed, the smooth surfaced endoplasmic reticulum (SER) was not yet differentiated. The typical peroxisomes with nucleoid and glycogen were not observed in the cytoplasm. On the 18th day the volumetric densities of hepatocytes and bile canaliculi were increased. The typical peroxisomes with nucleoid appeared in the cytoplasm. The accumulation of glycogen which amounted to 12% of the cytoplasmic volume had taken place, while the volume of lipid droplets decreased significantly. In glycogen areas the differentiation of SER began. At birth the histogenesis of the liver was well established. The hemopoietic cells decreased in number and were confined to perisinusoidal spaces. The volumes of biliary capillaries and sinusoids were comparable with these of young rats now. The volumetric density of hepatocytes increased and occupied about 74% of the liver. The volumetric densities of mitochondria, SER, peroxisomes, secondary lysosomes, and lipid droplets increased significantly in comparison with those of the 18 days old fetus, while RER, Golgi area, and primary lysosomes were rather constant. The volumetric density of glycogen decreased rapidly at birth.

The surface connected canalicular system of carp (Cyprinus carpio) thrombocytes: its fine structure and three-dimensional architecture

The presence and the three dimensional distribution of the surface connected canalicular system (SCCS) in thrombocytes of a teleost, Cyprinus carpio, were studied using a transmission electron microscope, a high voltage electron microscope and a scanning electron microscope. When the specimens were fixed routinely in glutaraldehyde followed by osmium tetroxide, numerous electron lucent vesicles and canaliculi were distributed throughout the cytoplasm. As ruthenium red-positive reaction product was observed on the inner surface of the vesicles and canaliculi, these are defined as the SCCS of carp thrombocytes. In the stereo-pair of the photographs of thick sectioned specimens and the plastic reconstruction of serially sectioned thrombocytes, we succeeded in finding the whole structure of the SCCS which is composed of numerous anastomosing canaliculi. Scanning electron micrographs revealed many crater-like depressions throughout the cell surface which seem to be the openings of the SCCS.

Fine structural distribution of the surface-connected canalicular system in frog thrombocytes

The existence of the surface-connected canalicular system (SCCS) has been demonstrated in semithick sections of the frog thrombocytes by the use of a high voltage electron microscope. The SCCS of the thrombocytes in Rana catesbeiana and Rana nigromaculata consists of numerous canaliculi and vesicles with a diameter of 250 nm, which join with one another to make a complex network throughout the cytoplasm. Although the SCCS of Xenopus laevis fits well into the pattern described in Rana catebeiana, the diameter of the canaliculi of the SCCS is about 500 nm. The results of this study suggest that the SCCS is a specific organelle of the thrombocyte system common to submammals and mammals.

Electron Microscopic Analysis of Subcellular Distribution and Translocation of Ca ION in Human Platelet

For the analysis of the subcellular distribution of Ca ion in human platelet, the washed platelet suspension was fixed in the potassium antimonate-OsO4 method or in the potassium oxalate-glutaraldehyde method without post-fixation with OSO4. The STEM-images were observed with scanning image system fitted with the transmission electron microscope without electron staining.

The dense deposition of antimonate or oxalate was found in plasmalemma, the membrane of open canalicular system, mitochondria, α-granules and dense bodies. It was revealed with the energy dispersive type electron probe x-ray microanalyzer system that the deposition of oxalate was exclusively composed of Ca.

In the process of platelet aggregation with various agents, α-granules and dense bodies were expelled out together with Ca, which suggested the least role of these ion depositions in the aggregation and clot retraction. The translocation of antimonate deposits was not observed in the Verapamil-treated platelets even after the addition of aggregation agents. This phenomenon indicated that this drug inhibited the release of Ca from the Ca-storing organelles. The distribution of Ca was identical in the platelets of a case of thrombasthenia and the translocation of Ca was not observed with the addition of various aggregating agents.

Ultrastructural localization of calcium around the membrane of the surface connected system in the human platelet

The localization of calcium in the membrane system of human platelets was determined by ultrahistochemical methods equipped with an electron probe x-ray microanalyzer. After potassium oxalate-glutaraldehyde treatment large amounts of electron opaque precipitates were observed around the membrane of the surface connected system. Electron probe x-ray microanalysis clearly defined that the precipitates were composed of calcium oxalate. The localization of calcium on the membrane of the surface connected system was also confirmed even after treatment of the platelets with potassium antimonate-OsO4. These results support a model which depicts the surface connected membrane system taking part in the store and the transport of calcium.