Endocrine cells of the human gastric mucosa

Summary By light and electron microscopy investigation of the human gastric mucosa five types of ultrastructurally different endocrine cells have been detected: 5-hydroxytryptamine storing enterochromaffin (EC) cells, gastrin storing G cells, and functionally undefined ECL, D and D₁ cells. By direct application of Masson's argentaffin reaction as well as of Sevier-Munger's and Grimelius' argyrophil method to electron microscopy specimens, selective deposition of silver grains upon the endocrine granules of such cells was obtained. In particular, only EC cell granules reacted to the argentaffin method, granules of both EC and ECL cells heavily reacted to Sevier-Munger's technique, granules of EC, ECL, G and D₁ cells reacted to Grimelius' technique, while D cell granules failed to react either to argentaffin or argyrophil methods. By the application of the same silver methods to paraffin sections as well as by other selective staining methods for endocrine granules (5-hydroxytryptamine techniques, lead-haematoxylin, HCl-basic dye method), at least four of the above cell types were also identified under light microscope. This opens the way for extensive studies of such cells in conventional histologie specimens.This investigation was supported in part by grant N.70.01022.04 from the Italian Consiglio Nazionale delle Ricerche.     

Electron microscopic demonstration of metals in rat mast cells

Summary This paper describes a modification of a cytochemical method for the demonstration of heavy metals. The well localized precipitate in the mast cell granules, which is also present in granules that have been separated from the cell, suggests that the metals are localized in the granules. It is demonstrated that mast cell grown cultures do not contain precipitate. The chelating and histamine inhibiting agent 8-hydroxyquinoline produced no changes in the histochemical pattern of the mast cell granules before nor after treatment with the histamine liberator 48/80 which provokes a release of granules from the cells. These observations suggest either that the metal (zinc) is bound to the granules in such a manner that the chelating agent cannot chemically, or based on the configurations of the metal-containing molecule, reach the metal and theraby prevent its transformation to a metal suphide.     

Double immunogold staining method for the simultaneous ultrastructural localization of regulatory peptides

Recent studies have suggested that the morphological characteristics of secretory granules contained within endocrine cells and nerves may be determined largely by their chemical composition. The use of the immunogold staining (IGS) method, which is based on the adsorption of colloidal gold to immunoglobulins, has been used in our laboratory to demonstrate a wide range of intracellular antigens at both the light and electron microscope levels. In this study we have applied a modification of the IGS method for the simultaneous detection of two separate antigens in a single tissue section, using a variety of region-specific antisera to different peptides. Peptide antisera were raised in rabbits or in guinea pigs and these were applied simultaneously or sequentially to grid-mounted ultrathin tissue sections. Antigenic sites were visualized at the electron microscope level using antisera raised in goats, adsorbed to gold particles of 12, 20, or 40 nm. Using this technique we have attempted to investigate the coexistence of multiple antigens in single tissue sections, in particular in single granules; the topographic distribution of molecular forms within one single granule or granule population; the heterogeneity of peptidergic neurons and also the heterogeneity of peptide content in morphologically similar granules. The double immunogold staining procedures described here have proved to be extremely effective for the simultaneous ultrastructural localization of two antigens (peptide-peptide; peptide-propeptide) on a single tissue section. The further development of this technique may provide useful information on neuroendocrine cell dynamics in normal and diseased states.     

Relationship between Rous sarcoma virus production in golden hamster cells and the cell cycle]

The axon terminals of neurosecretory cells, containing elementary granules of neurosecretory materials, have been described on the basis of light and electron microscopy. No allochthonous neurosecretory elements were found in the sinus gland. The discharge of the granules from some terminals of the sinus gland occur with the changed salinity of the environment. There is a great difference in the structure of the sinus gland when salinity is changed. The structure of the sinus gland and its modification under experimental conditions indicate a possibility of neurohormonal regulation of the hydromineral balance.     

A Kinetic Study of the Polymorphic Transformation of Nimodipine and Indomethacin during High Shear Granulation

The objective of the present study was to investigate the mechanism, kinetics, and factors affecting the polymorphic transformation of nimodipine (NMD) and indomethacin (IMC) during high shear granulation. Granules containing active pharmaceutical ingredient, microcrystalline cellulose, and low-substituted hydroxypropylcellulose were prepared with ethanolic hydroxypropylcellulose solution, and the effects of independent process variables including impeller speed and granulating temperature were taken into consideration. Two polymorphs of the model drugs and granules were characterized by X-ray powder diffraction analysis and quantitatively determined by differential scanning calorimetry. A theoretical kinetic method of ten kinetic models was applied to analyze the polymorphic transformation of model drugs. The results obtained revealed that both the transformation of modification I to modification II of NMD and the transformation of the α form to the γ form of IMC followed a two-dimensional nuclei growth mechanism. The activation energy of transformation was calculated to be 7.933 and 56.09 kJ·mol⁻¹ from Arrhenius plot, respectively. Both the granulating temperature and the impeller speed affected the transformation rate of the drugs and, in particular, the high shear stress significantly accelerated the transformation process. By analyzing the growth mechanisms of granules in high-shear mixer, it was concluded that the polymorphic transformation of NMD and IMC took place in accordance with granule growth in a high-shear mixer.     

Staining of rabbit eosinophil and pseudoeosinophil leukocytes.

Air-dried rabbit blood was stained by HE, PAS and a modification of the Undritz II method. Eosin stained granules red in the eosinophil leukocytes. PAS was negative and the modified Undritz method failed to give consistent results. Cells with eosinophilic granules appeared in the corneal stroma 1 h after removing the corneal epithelium. They were stained red consistently by both eosin and the modified Undritz II method. Electron micrographs failed to demonstrate crystalloids in the granules. Because of the staining characteristics and the lack of crystalloids in their granules these cells were classified as pseudoeosinophil leukocytes. The electron micrographs showed some glycogen 12 h after denuding the cornea, however, glycogen was not well stained by PAS until 18 h after denuding.     

Precocious loss of cortical granules during mouse oocyte meiotic maturation and correlation with an egg-induced modification of the zona pellucida

Fertilization results in cortical granule exocytosis, which is thought to be involved in modifications of the zona pellucida that constitute the zona pellucida block to polyspermy. A previous report demonstrated that a decrease in the number of Lens culinaris agglutinin-staining granules, which are likely to be cortical granules, occurred during in vivo mouse oocyte maturation with arrest at metaphase II, as well as the formation of a cortical granule-free domain in the area of the metaphase II spindle (T. Ducibella, E. Anderson, D.F. Albertini, J. Aalberg, and S. Rangarajan, 1988, Dev. Biol. 130, 184-197). We extend these observations by reporting here that germinal vesicle-intact oocytes matured in vitro to metaphase II in either the absence or the presence of serum develop a cortical granule-free domain and have reduced numbers of cortical granules when compared to germinal vesicle-intact oocytes; these changes are similar to those of oocytes matured in vivo. The reduction in the number of cortical granules requires germinal vesicle breakdown, since it is prevented by dibutyryl cAMP, which inhibits germinal vesicle breakdown in vitro. The ability of oocytes to respond to the calcium ionophore A23187 with a reduction in the number of cortical granules is also associated with meiotic maturation and develops between 7 and 12 hr after initiation of maturation. The maturation-associated reduction in the number of cortical granules is likely to represent cortical granule exocytosis, since this reduction is accompanied by the formation of a cortical granule-free domain and a conversion of ZP2 to ZP2f when the oocytes are matured in vitro in serum-free medium; this zona pellucida modification occurs following fertilization and is thought to be due to cortical granule exocytosis. In contrast, the loss of cortical granules and development of the cortical granule-free domain of oocytes matured in vitro in the presence of serum is not accompanied by the modification of ZP2. The inhibitory effect of serum on the ZP2 modification may afford in vivo a physiological mechanism to prevent a precocious modification of the zona pellucida that could result in a premature block to polyspermy and hence inhibit fertilization.     

Ultrastructural observations on the biogenic amines in the carotid and aortic-abdominal bodies of the human fetus

Summary The carotid and aortic-abdominal bodies of two human fetus at fifth month of pregnancy have been studied with the light and electron microscope. A personal variation of the glutaraldehyde ammoniacal silver (GA/S) method has been used, which consists in performing the silver reaction on the ultramicrotomical sections of the tissues, first fixed by glutaraldehyde perfusion and then included in Epikote 812.In the light microscope, the GA/S reaction is certainly positive in the aortic-abdominal bodies and it is negative or dubious in the carotid bodies. — In the electron microscope, however, the reaction is positive both in the aortic-abdominal and in the carotid bodies. — In the aortic-abdominal bodies, the silver precipitate accumulates into thick cytoplasmic granules, which have been shown to be NA-storing granules. — In the carotid bodies however, the silver precipitate accumulates into much smaller cytoplasmic granules, which are interpreted as 5-HT-storing granules.     

Electron microscopic demonstration of calcitonin in human medullary carcinoma of thyroid by the immuno gold staining method

In a human medullary carcinoma of thyroid gland containing calcitonin in light microscopic demonstration by the avidin biotin complex (ABC) method characteristic secretory granules were found electron microscopically in the cytoplasm of the tumour cells. They consisted in so-called type I granules (270 +/- 25 nm) and type II granules (135 +/- 17 nm). By the immuno gold staining (IGS) method the content of many secretory granules measuring 85-270 nm (152 +/- 18 nm) in diameter could be identified as calcitonin. These granules seemed to be predominantly of type II because of their nearly corresponding size and feature. The type I granules were less frequent in number and they showed no or little immunoreactivity. The results indicate that the IGS-method is practicable to demonstrate the ultrastructural localization of calcitonin and to identify clearly the nature of intracytoplasmic granules in electron microscopy.     

Esterase and protease activity of purified guinea pig basophil granules.

Highly purified granules of circulating guinea pig basophilic leukocytes were extracted with 0.1% Triton X-100 to yield a mixture of esterases-proteases including caseinolytic activity. By selective inhibition both trypsin- and chymotrypsin-like serine hydrolases have been identified. Sigmoidal pH dependences for hydrolysis of p-tosyl-L-arginine-methyl ester and N-benzoyl-L-tryosine-ethyl ester were observed for both intact granules and Triton granule extracts. Preliminary studies indicate that the enzymes are not solubilized even after Triton X-100 treatment of the granules.     

Storage, ultrastructural targeting and function of toposomes and hyalin in sea urchin embryogenesis.

This study compares by immunogold labeling the ultrastructural localization of a hexameric 22S glycoprotein, called toposome, with that of hyalin in unfertilized eggs and cells of hatched sea urchin blastulae. Nearly all hyalin is present in the electron translucent compartment of the cortical granules and in the translucent non-cortical pigment granules. In the blastula both of these intracellular stores have vanished and hyalin now forms a broad band below the apical lamina. By contrast, in the egg toposomes are present on the surface, as well as stored in yolk granules and in the electron dense lamellar compartment of the cortical granules. In the hatched blastula, toposomes that have been modified by limited proteolysis in the yolk granules, are associated with the plasma membranes of all newly formed cells, while the toposomes originating from the cortical granules have been incorporated as unmodified 160 kDa polypeptides into an extracellular double layer enveloping the embryo on the outside of the hyaline layer. From evidence discussed in detail, we conclude that the extracellular toposomes rivet the apical lamina to the surface and underlying cytoskeleton of the microvilli, while the modified toposomes from the yolk granules are responsible for position specific intercellular adhesion as they are released to the surface of newly formed cells. We propose that all the material stored in yolk granules is utilized for the assembly of new membranes.     

Immunocytochemical localization of atrial natriuretic peptide in endothelial and granular cells of the heart of lophotrochozoa

In parallel with contraction, vertebrate cardiomyocytes perform endocrine function and produce natriuretic peptides (NP)--ANP and BNP--involved in cardiovascular homeostasis maintenance. ANP-like peptides have been reported also in hearts of some invertebrates, however, their cellular localization was not determined. By electron microscopical immunocytochemistry with polyclonal monospecific antibodies raised against ANP and protein A-gold technique, we have localized ANP-like immunoreactivity in granules within endothelial cells in the heart of the brachiopod Rhynchonella psittacea, the polychaete Arenicola marina, and the gastropod mollusc Achatina fulica--all being representatives of the major phylogenetic group Lophotrochozoa. ANP-like immunoreactivity was also revealed in one of 3 morphologically distinguishable types of granules in the snail heart granular cells. By electron microscopical autoradiography with the use of [3H]-thymidine, the ability for DNA synthesis was demonstrated in heart endothelial cells of the investigated animals. Forms of NP-system organization in hearts of Lophotrochozoa and Vertebrates, and close histogenetic relationships of endothelial and granular cells in the snail heart are discussed.     

Electron microscopic demonstration of calcitonin in human medullary carcinoma of thyroid by the immuno gold staining method

Summary In a human medullary carcinoma of thyroid gland containing calcitonin in light microscopic demonstration by the avidin biotin complex (ABC) method characteristic secretory granules were found electron microscopically in the cytoplasm of the tumour cells. They consisted in so-called type I granules (270±25 nm) and type II granules (135±17 nm). By the immuno gold staining (IGS) method the content of many secretory granules measuring 85–270 nm (152±18 nm) in diameter could be identified as calcitonin. These granules seemed to be predominantly of type II because of their nearly corresponding size and feature. The type I grnaules were less frequent in number and they showed no or little immunoreactivity. The results indicate that the IGS-method is practicable to demonstrate the ultrastructural localization of calcitonin and to identify clearly the nature of intracytoplasmic granules in electron microscopy.     

Pt-staining of peroxidatic reaction products at the ultrastructural level

The use of H2PtCl6 is proposed for the selective visualization of the poly-DAB reaction product created, in aldehyde-fixed tissue, with the cytochemical reaction according to Graham and Karnovsky (1966) or to Hoefsmit (1975). At sites known to contain peroxidatic activity, at the ultrastructural level, an electron-dense reaction product is acquired in otherwise unstained ultrathin sections. The presence of the element platinum in these sites has been demonstrated by X-ray microanalysis, for both the endogenous peroxidase and peroxidase conjugated to antibodies. The absolute platinum concentration has been established in erythrocytes and the granules in eosinophils and monocytes by co-embedded, Pt-containing Chelex ion-exchange beads next to the cells. By the application of the method of integrated morphometrical and chemical analysis (de Bruijn and Zeelen 1984; de Bruijn 1985; de Bruijn and Cleton 1985), both the elemental concentration and the area occupied have been calculated for eosinophil granules. The mean Pt net-intensity values of the cytoplasmic areas, known not to contain the enzyme peroxidase has been measured, and compared to the mean net-intensity Pt values of the granules. It was noted that the cytoplasmic Pt net-intensity values were not zero. The two sets of values are expressed as a mean Pt granule/cytoplasm ratio, this ratio creates a value for the "selectivity" of the reaction. The application of a postfixation reaction with OsO4- containing media, at pH 7.4, in addition to the H2PtCl6 reaction, resulted in a contrasted poly-DAB reaction product at all sites known to contain peroxidatic activity. However, X-ray microanalysis revealed that in addition to platinum, osmium was present.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mosquito trypsin: immunocytochemical localization in the midgut of blood-fed Aedes aegypti (L.)

Summary A polyclonal antibody was raised against trypsin purified from the midgut of blood-fed Aedes aegypti. Using this antibody and our modification of the peroxidase-antiperoxidase immunocytochemical reaction, strong activity was found in the lumen of the midgut at the light-microscopical level. The activity was localized mainly in the posterior part of the distensible, abdominal midgut, along the periphery of the blood bolus and within the peritrophic membrane. Immunoreactivity appeared 8 h after the blood meal and was most prominent around 24 h, coinciding with our previous spectrophotometric determinations of trypsin.At the electron-microscopical level, secretory granules, immunocytochemically labelled with anti-trypsin antibody and protein A-colloidal gold, were first detected about 12 h after the blood meal. At 18 h, the secretory pathway could be followed immunocytochemically from the formation of granules in the Golgi complex until their release by exocytosis in the midgut lumen. By 24 h, there was a reduction in secretory granules, and large lysosomes appeared.The process of secretion described for this mosquito is comparable to similar events in vertebrate secretory systems and the presence of an intracellular trypsinogen is suggested.     

Colloidal gold, a useful marker for transmission and scanning electron microscopy.

Electron dense markers of a size suitable for transmission electron microscopy and scanning electron microscopy have been prepared with gold granules labeled with a monolayer of specific macromolecules. The optimum conditions for preparing the markers have been ascertained. The method is simple, rapid and seems to be general since gold granules have been labeled with polysaccharides and proteins. As homogeneous populations of gold granules having different sizes can be prepared, the method is also suitable for double marking experiments. The gold technique is illustrated by the localization of polysaccharides and glycoproteins on yeast cell walls and erythrocyte membranes by transmission electron microscopy and on yeast cells and intact erythrocytes by scanning electron microscopy. Good spatial resolution of the marker was achieved in all cases. The method is also suitable for marking thin sections. Spectrophotometric measurements were used to determine the number of gold granules adsorbed per cell.     

Association of rap1 and rap2 proteins with the specific granules of human neutrophils. Translocation to the plasma membrane during cell activation.

Activation of human neutrophils involves the degranulation of specific and azurophil granules. This process is GTP-dependent and the presence of small GTP-binding proteins (SGBPs) has been detected in the two granule populations. At present, none of these SGBPs has been definitely identified. In order to characterize some of these proteins and obtain further insights as to their potential role in degranulation processes, we have used specific antibodies directed against the ras-related rap1 and rap2 proteins. By immunoblot analysis, we observed that rap2p is predominantly located in specific granules, whereas rap1p is detected both in specific granules and a fraction enriched in plasma membranes. Neither rap1p nor rap2p was found in the cytosol or in azurophil granules. Similarly, by indirect immunofluorescence, we observed that cytoplasmic granules were stained with anti-rap1p antibodies and anti-rap2p antibodies, and the plasma membrane was labeled with both antibodies but more distinctly with anti-rap1p than with anti-rap2p antibodies. rap1p and rap2p are tightly bound to the membrane of specific granules since they cannot be extracted by high salt or alkaline buffers. In addition, treatment of intact specific granules with pronase induced the degradation of rap proteins suggesting that they are exposed to the cytoplasmic face of the granules. Degranulation of neutrophils consists of the translocation and subsequent fusion of granules with the plasma membrane. Activation of this process induced the accumulation of rap proteins in the plasma membrane as observed by subcellular fractionation and indirect immunofluorescence experiments; this was not associated with the appearance of a soluble form of these proteins, showing that they remain membrane-bound during this process. The identification and subcellular localization of rap1p and rap2p at the surface of specific granules and the observation that they translocate to the plasma membrane upon cell stimulation without appearance of soluble forms constitute an important step toward the understanding of their physiological functions in human neutrophils.     

Non-lipid osmiophilic granules in the presynaptic neuroplasma of the boutons

Summary Brain, spinal cord and peripheral (sensory and sympathetic) ganglia of cats and rats have been fixed in Susa, imbedded and impregnated on slides with a mixture of osmium tetroxide and egg albumen solution.This method produced small (about one micron) black granules in the boutons around the multipolar nerve cells in the cord and in the medulla. The granules were absent around the other nerve cells in the cortex (pyramidal cells, etc.) and in the peripheral ganglia.These osmiophilic granules may be clusters of synaptic vesicles containing transmitter substance. If the clusters are large enough, as in the boutons, they are visible under the light microscope, if they are smaller;, as in the smaller synaptic knobs, they remain invisible.If the osmiophilic granules are clusters of vesicles containing the transmitter substance, this substance might be an acidic amino acid.