Tateo Daimon

Localization of copper to afferent terminals in rat locus ceruleus, in contrast to mitochondrial copper in cerebellum.

We examined copper localization in the locus ceruleus and cerebellum of rat brain by Timms sulfide-silver staining, as modified by Danscher. Dense silver particles revealing copper localization were observed in sections of the locus ceruleus and cerebellum after pre-treatment with trichloroacetic acid. In the locus ceruleus, copper appeared to be distributed to neuropil rather than glial or neuronal cell bodies, and at the ultrastructural level copper was mainly localized on synaptic membranes of afferent terminals in contact with somatic spines or dendrites of locus ceruleus neurons, whereas copper was distributed to mitochondria in the granular layers of cerebellum and fine, sparse silver particles were observed throughout ependymal cells and epithelial cells of blood vessels. The specific localization of copper to afferent terminals in the locus ceruleus was confirmed by X-ray microanalysis, which showed a significant level of copper, but not zinc, in synaptic membranes. These results suggest a distinct role of copper depending on its regional distribution. Copper or copper protein may be involved in neurotransmission in the locus ceruleus but in mitochondrial activity in the cerebellum.

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

SummaryThe 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.

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

SummaryThe 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.

Ultrastructural localization of acid protein polysaccharides and calcium in the vacuoles of the chicken thrombocyte.

SummaryThe coexistence of acid protein polysaccharides and calcium in the vacuoles of chicken thrombocytes were studied by means of ultrahistochemical methods and electron probe X-ray microanalysis.The thrombocytes possessed large vacuoles of a surface connected membrane system. After both ruthenium red staining and tannic acid fixation the innersurface coat of vacuoles was always strongly and continuously visualized. Electron microscopic X-ray microprobe analysis of antimonate precipitates in thrombocytes fixed in K-antimonate-OsO4 revealed calcium localization on the innersurface of vacuoles. From these facts it seems likely that the vacuoles of the surface connected membrane system may take part in the pool or the transport of calcium.

Immunocytochemical localization of thrombomodulin in the aqueous humor passage of the rat eye.

Abstract This report describes the distribution and localization of thrombomodulin (TM) in the rat eye by light and electron microscopic immunocytochemistry. In addition to the endothelium of the entire vasculature, TM was found on the non-vascular structures lining the cavities of the posterior and anterior chambers and the limbus. TM was localized on the basal, lateral, and apical plasma membranes of the inner and outer ciliary epithelium, and the posterior iris epithelium in which there was no polarized expression of TM. In the anterior chamber, TM was localized on the luminal surface of the corneal endothelium, but was negative on the anterior border layer of the iris, which is composed of a discontinuous layer of fibroblasts and collagen fibers. Thus, TM was present at sites of cell-to-cell contact. TM was also present on the endothelia of the trabecular meshwork and the Schlemm’s canal in the limbus. TM was localized not only on the luminal plasma membrane, but also on the cytoplasmic giant vacuoles in the endothelial cells of the Schlemm’s canal. These findings extend the importance of anticoagulant mechanisms to the systems of secretion, circulation, and drainage of the aqueous humor.

Cytochemical evidence of the origin of the dense tubular system in the mouse platelet

SummaryGlucose-6-phosphatase (G6Pase) was used as a marker enzyme for the endoplasmic reticulum in mouse megakaryocytes and platelets. G6Pase activity was localized in the dense tubular system of the platelets. Enzyme activity was also observed in the nuclear envelope, and in the rough endoplasmic reticulum of the megakaryocytes. However, the Golgi apparatus of the megakaryocyte was never involved. The present study has added new cytochemical evidence for the hypothesis that the dense tubular system of the platelet originates from the endoplasmic reticulum of the megakaryocyte.

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

SummaryThe 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 catesbeiana, 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.

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

SummaryIdentification and distribution of the precursors of aminestorage 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 precursory organelles increased gradually during cell maturation and became almost equivalent to the dense body of blood platelets in the final stage of cell maturation.

Cytochemical Demonstration of Amine-storing Vacuoles and Lysosomes in the Chicken Thrombocytes

SummaryA combined electron microscopic and cytochemical study of the thrombocytes of the chicken has clearly identified the amine-storing organelles and lysosomes. A chormaffin positive-reaction product was observed on the inner surface and the granules of the large electronlucent 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.

Ultrastructural distribution of peroxidase in thrombocytes of mammals and submammals

SummaryThe 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 deteetable 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.