Intracellular localization of calcitonin in the C cells of the rat.

Specific localization of C cells at the electron microscope level was achieved by an indirect immunoperoxidase technique. The hormone is present in the electron dense granules. The presence of granules apparently devoid of calcitonin was also detected.     

Reinterpretation of the ultrastructure of cartilage matrix.

The epiphyseal cartilage from new-born mouse was treated with collagenase in two ways: either before fixation or after glutaraldehyde fixation. The electron dense granules of the matrix were not seen in the micrographs of cartilage treated with collagenase before fixation. It is concluded that collagen plays a definite role in the formation of the granules at the time of tissue fixation and that the granules are fixation artifacts.     

Reinterpretation of the ultrastructure of cartilage matrix

Summary The epiphyseal cartilage from new-born mouse was treated with collagenase in two ways: either before fixation or after glutaraldehyde fixation. The electron dense granules of the matrix were not seen in the micrographs of cartilage treated with collagenase before fixation. It is concluded that collagen plays a definite role in the formation of the granules at the time of tissue fixation and that the granules are fixation artifacts.Commonwealth Academic Staff Fellow. Permanent address: Department of Zoology, University of Poona, Poona 411007, India.     

A preliminary report on the fine structure of Tripneustes esculentus eggs.

The fine structure of Tripneustes esculentus eggs was studied with the aid of an electron microscope. Cells obtained from this West Indies sea urchin showed cortical granules, mitochondria forming a rosette around lipid granules, endoplasmic reticula, Golgi apparatus and annulated lamellae. These structures appear identical to those seen in eggs of the Atlantic sea urchin: Arbacia punctulata.     

Ultrastructure of neurosecretory granules in the sinus gland of Palaemon serratus Pennant]

Five types secretory granules are distinguished in the sinus gland of Palaemon serratus on the basis of differences in their diameter and their electron density. Variations in the density of the acoplasm and of the granules are observed for three of these granule types.     

Secretory phenomenon of the adenohypophyseal cells viewed with the scanning electron microscope

Summary Exocytosis from rat adenohypophyseal cells, probably somatotrophic, was studied in the scanning electron microscope after freeze fracturation of the glands. This technique permitted the distinguishing of a clearly delimited exoplasm interrupted by the passage of the secretory granules. It was postulated that the exoplasm could be involved in the control of the release of secretory granules in the endocrine cells studied. At the basal cell surface a simultaneous discharge of several secretory granules has been detected.With the technical assistance of Mr P.-A. Milliquet.     

Association of intermediate filaments with other cell organelles in carcinoid tumor of the colon.

Carcinoid tumor of the colon was studied in electron microscope. In cytoplasm, prominent intermediate-sized filaments were seen frequently attaching to nucleus and mitochondria. Direct contacts of intermediate filaments with secretory granules were not observed.     

Peroxidase activity of neutrophil granules in two cases of congenital myeloperoxidase deficiency]

The neutrophils and monocytes of two patients with hereditary myeloperoxidase deficiency lacked myeloperoxidase activity as determined by light and electron microscopic cytochemical staining. Using Graham-Karnovsky media, azurophils of neutrophils were devoid of peroxidase whereas all eosinophilic and basophilic granules exhibited normal peroxidase activity. After incubation in alkaline diaminobenzidine media which stains the catalase of microperoxisomes, some small granules were seen to be strongly stained in both immature and mature neutrophils. These small granules were distinct from all other neutrophilic granules which lacked a positive reaction. Only, in the presence of cyanide or aminotriazole, peroxidatic activity was also detected in some ellipsoid azurophils. This observation suggests that these substances activated an oxidase whose nature is discussed.     

Presence of presumptive interdigitating cells in the spleen of the natterjack,Bufo calamita

Summary The periphery of splenic lymphoid follicles, an area rich in reticulum fibers, contains presumptive interdigitating cells characterized by low electron density, scantiness of cytoplasmic organelles, abundant surface foldings and, sometimes, electrondense granules of unknown significance.     

A method for the isolation of ommochrome-containing granules from insect eyes

Summary A routine method for the preparation of pigment granules from insect eyes is reported. When viewed using an electron microscope, the isolated granules appear to be free from different structural elements, and there is very little contamination by membranous material. Ultrastructure and extinction spectra correspond to those found in situ.Acknowledgments. We thank Prof. Dr A. Fischer and Dr J. Rosenberg for their help in electron microscopic techniques. This work was supported by the Deutsche Forschungsgemeinschaft.     

Elektronenmikroskopische Untersuchungen an den heterophilen Granulozyten des Haushuhns

Summary Ultra-thin sections of heterophil granulocytes of clinically healthy, laying hybrid-hens were examined by electron microscope. Within the cytoplasm of these cells, round, oval or fusiform granules (rods) of different electron density were found. Osmiophilic and electron light areas (cores) were seen, either together within the same granular body, or separately in different granules.     

Immunocytochemical anatomy of alpha granules in the human endocrine pancreas]

Using the sensitive protein A-gold technique for the demonstration of antigenic sites in thin section for electron microscopy it was found that in the alpha granules of human pancreas, glucagon immunoreactivity (specific, C-terminal) is restricted to the dense granule core while glicentin immunoreactivity predominates on the peripheral halo surrounding the dense core.     

Association of intermediate filaments with other cell organelles in carcinoid tumor of the colon

Summary Carcinoid tumor of the colon was studied in electron microscope. In cytoplasm, prominent intermediate-sized filaments were seen frequently attaching to nucleus and mitochondria. Direct contacts of intermediate filaments with secretory granules were not observed.Acknowledgments. The skilful technical assistance of Ms Tuire Koro is gratefully acknowledged. — This study was supported by grants from the Finnish Medical Research Council, Finnish Culture Foundation and J.K. Paasikivi Foundation for Cancer Research.     

Immunohistochemical localization by electron microscopy of GnRH in the median eminence of Xenopus laevis daud]

Using antibodies against mammalian LHRH with the unlabeled antibody enzyme method immunoreactive nerve fibres were localized in the median eminence of Xenopus laevis at the electron microscopic level. These fibres contain irregularly shaped neurosecretory granules with an average diameter of 890 A.     

The EM immunocytochemical demonstration of lysozyme in macrophage giant cells in sarcoidosis.

The giant cells (multinucleate macrophages) of human sarcoidosis have been shown by the unlabelled antibody immunoperoxidase technique at electron microscope level to contain lysozyme within cytoplasmic granules.     

Ultrastructural localization of vanadium in the blood cells of Ascidiacea.

X-ray histospectrographic analysis at the scanning and transmission electron microscope (STEM) are made on the blood cells of Phallusia mamillata Cuvier and Ciona intestinalis, to study the 'direct' intracellular sites of accumulation of vanadium. The results show a clear accumulation of vanadium on the membrane and in the granules of vacuoles of amebocytes, signet ring cell, compartment cell and traces of metal in the 'vanadophores' of vanadocytes.     

Differentiation of human megakaryocytes in culture starting from the primordial circulating cells in the newborn]

Human neonatal blood mononuclear cells were seeded in plasma clot containing high dose of a crude erythropietin. Pure megakaryocyte colonies were observed rarely and most of the colonies were mixed, megakaryocytes being located between subcolonies of erythrocytic bursts. The megakaryocytic nature of large cells could be clearly confirmed by the presence of platelet peroxidase, demarcation membranes, and alpha granules detected by electron microscopy; in addition mature micromegakaryocytes were recognized, shedding platelets.     

Simple methods for observing cortical granules in living mammalian eggs

Summary Simple light microscopic methods for routine observation and checking cortical granules of vital mammalian eggs will be described. By using interference contrast and dark field techniques, even small cortical granules can easily be examined. These methods are time-saving compared to the usual ones using an electron microscope. They make distribution studies possible without difficulties.     

Ultrastructure of epiphyseal cartilage after extraction on thin sections of "Epon" of proteoglycans by calcium chloride]

Dissociative methods are commonly used to extract proteoglycans. With a 2 M CaCl2 solution these components can be also extracted from thin sections of fixed, "Epon" included material. Secretory granules of the chondrocytes, granular components of extracellular matrix as matrix vesicles lost their electron density. Glycoproteins of the cell coat as non collagenous glycoproteins disappear. The method seems to be valuable for extracting proteoglycans from thin sections prepared for electron microscope investigations.     

X-ray microanalysis of mast cells in rat's muscle

Summary Mast cells from rat's tongue muscles, fixed with glutaraldehyde only, were examined with an electron microscopic microanalyzer — the EMMA-4. With the preparatory method used, high emissions of a number of elements were obtained in various intracellular spots. The granules of mast cells were found to contain strictly localized high concentrations of sulphur, calcium and zinc.This work was supported by a grant from the MRC. Funds for the purchase and running cost of the instrumentation were provied by the SRC.