Alcian Blue staining of cartilage for electron microscopy. Application of the critical electrolyte concentation principle.

The critical electrolyte concentration principle was applied to the Alcian Blue staining of rat epiphyseal cartilage proteoglycans for electron microscopy. The distribution and structure of material in glutaraldehyde-fixed cartilage stained at pH 5.8 without MgCl2 and in the presence of 0.05, 0.4, 0.5, 0.9 and 1.0 M MgCl2 was compared with that produced by simultaneous staining and fixation at neutral pH. Both methods resulted in staining of intracellular material within vacuoles as well as staining of non-collagenous matrix material. The structure and distribution of Alcian Blue-positive matrix material consisted of rounded or polygonal granules which accumulated around cells in the proliferative and hypertrophied zones. A similar pattern of distribution was observed in samples stained in the presence of 0.4 or 0.5 M MgCl2. In these cases, however, the stained material exhibited a ribbon-like configuration and granules were few in number. Increasing the MgCl2 concentration to 1.0 M resulted in a marked reduction of Alcian Blue stained material. No ribbon-like structures were observed, and matrix granules were reduced in both number and size. The decreased staining associated with increased electrolyte concentration lends support to the concept that epiphyseal cartilage matrix granules are composed primarily of chondroitin sulphate, and suggest that this same material is present in vacuoles associated with the Golgi apparatus in chondrocytes of the proliferative and hypertrophying zones.     

Carbohydrate cytochemistry of the intestinal epithelium of Ascaris suum. Nature of the microvilli glycocalyx and basal lamella.

Results of various cytochemical tests demonstrate large deposits of glycogen within the intestinal absorptive cells of Ascaris suum. Carbohydrate material is also associated with the microvilli surface and basal lamella. Staining produced by the periodate-thiocarbohydrazide-osmium procedure was abolished by analine or m-aminophenol. Diastase digestion did not alter the staining on the microvilli surface. Similar results were seen using the silver methenamine procedure. A positive reaction was noted on the microvilli surface, vesicles in both the apical and basal cytoplasm, Golgi apparatus, and basal lamella. Lanthanum nitrate stained the microvilli surface and intercellular spaces between absorptive cells. Alcian blue or cetylpyridinium chloride in combination with lanthanum enhanced the staining produced by lanthanum alone. These results suggest the presence of acidic glycans on both the microvilli surface and basal lamella.     

Correlation between Alcian Blue staining of glycosaminoglycans of cat nucleus pulposus and TEM X-ray probe microanalysis

Synopsis The nucleus pulposus of cat intervertebral disc was examined after staining glycosaminoglycans with Alcian Blue and the results correlated with TEM X-ray probe microanalysis. In unstained sections a difference in copper levels between tissues and resin was detected. In tissue stained with Alcian blue before embedding, the copper levels were slightly increased and the morphological appearance of the intercellular material was amorphous. In sections restained after cutting, the relative levels of copper in the resin were considerably increased and tissue levels were significantly higher than in the resin. Moreover, the morphology of the intercellular material was altered from a rather amorphous material to a network. Sulphur levels behaved in similar manner to copper levels but any correlation between the elements was due to factors unrelated to glycosaminoglycan staining and probably resulted from contaminating sulphur.     

Freeze-substitution staining of rat growth plate cartilage with alcian blue for electron microscopic study of proteoglycans

To selectively stain polyanionic macromolecules of growth plate cartilage and to prevent artifacts induced by aqueous fixation, proximal tibial growth plates were excised from rats, slam-frozen, and freeze-substituted in 100% methanol containing the cationic dye Alcian blue. Electron microscopic examination showed the tissue stained with Alcian blue to be comparable in ultrastructural preservation to tissues slam-frozen and freeze-substituted in the absence of Alcian blue. The extracellular matrix exhibited a characteristic staining pattern when stained by this method. The pericellular rim was identified as a band of varying width encircling the chondrocyte and its cell processes. Peripheral to the pericellular rim the heterogeneity of staining within the extracellular matrix increased, taking the form of polymorphic densities. X-ray microanalysis showed that the visual interpretation of electron density was related to the concentration of copper present, and that the concentration of sulfur was variable in the pericellular rim and in the interterritorial matrix. The difficulties associated with aqueous fixation and staining procedures are discussed in contrast to the improved preservation achieved by cryogenic methods.     

X-ray microanalysis of toluidine blue stained chromosomes: a quantitative study of the metachromatic reaction of chromatin

Summary The stoichiometry of metachromatic staining of chromatin by toluidine blue was investigated in isolated metaphase chromosomes from L929 cells using X-ray microanalysis. Microspectrophotometric measurements revealed that a hypsochromic shift (from 595 to 570 nm) occurs in toluidine blue stained chromosomes in relation to the staining solution. Under the electron microscope, stained chromosomes showed higher electron density than control chromosomes. After toluidine blue staining, X-ray microanalysis of chromosomes revealed a large increase for sulphur counts and a considerable increase for Fe and Cu counts, while the signal of Mg, Ca, Cl, K and Zn was reduced. After subtraction of the intrinsic sulphur signal, S/P ratios of 0.82 — for euchromatic arms — and 0.85 — for centromeric heterochromatin — were obtained. They are considered representative of dye/DNA phosphate ratios. These results indicate the occurrence of a nearly stoichiometric binding of toluidine blue to chromatin DNA and suggest that an external dye stacking is responsible for the metachromatic staining of metaphase chromosomes.     

X-ray microanalysis of toluidine blue stained chromosomes: a quantitative study of the metachromatic reaction of chromatin

The stoichiometry of metachromatic staining of chromatin by toluidine blue was investigated in isolated metaphase chromosomes from L929 cells using X-ray microanalysis. Microspectrophotometric measurements revealed that a hypsochromic shift (from 595 to 570 nm) occurs in toluidine blue stained chromosomes in relation to the staining solution. Under the electron microscope, stained chromosomes. After toluidine blue staining, X-ray microanalysis of chromosomes revealed a large increase for sulphur counts and a considerable increase for Fe and Cu counts, while the signal of Mg, Ca, Cl, K and Zn was reduced. After subtraction of the intrinsic sulphur signal, S/P ratios of 0.82--for euchromatic arms--and 0.85--for centromeric heterochromatin--were obtained. They are considered representative of dye/DNA phosphate ratios. These results indicate the occurrence of a nearly stoichiometric binding of toluidine blue to chromatin DNA and suggest that an external dye stacking is responsible for the metachromatic staining of metaphase chromosomes.     

LANTHANUM STAINING OF THE SURFACE COAT OF CELLS : Its Enhancement by the Use of Fixatives Containing Alcian Blue or Cetylpyridinium Chloride

Among the techniques which have been reported to stain the surface coat of cells, for electron microscopy, is lanthanum staining en bloc. Similarly, the presence of the cationic dye, Alcian blue 8GX, in a primary glutaraldehyde fixative has been reported to improve the preservation of the surface coat of cells of many types; however, the preserved coat is not very electron opaque unless thin sections are counterstained. The present paper shows that for several rat tissues lanthanum staining en bloc is an effective electron stain for the cell surface, giving excellent contrast, if combined sequentially with prefixation in an aldehyde fixative containing Alcian blue. The cationic substance cetylpyridinium chloride was found to have a similar effect to that of Alcian blue in enhancing the lanthanum staining of the surface coat material of the brush border of intestinal epithelial cells. The patterns of lanthanum staining obtained for the tissues studied strikingly resemble those reported in the literature where tissues are stained by several standard methods for demonstrating mucosubstances at the ultrastructural level. This fact and the reproduction of the effect of Alcian blue by cetylpyridinium chloride constitute a persuasive empirical argument that the material visualized is a mucopolysaccharide or mucopolysaccharide-protein complex.     

The fine structure of the stomach mucosa of the llama (Llama guanacoe)

Summary The epithelium of the fundic region mucosa of the hind stomach in the Llama guanacoe has been studied using morphological and histochemical methods. Morphology suggests that solute and water absorption may occur in the epithelium of the surface and of the foveolae, although this absorption can not be estimated because of the extensive secretion of the gastric glands. The same cells of the surface and foveolar epithelium show numerous secretory granules. The glands reveal neck cells, chief cells, a large number of oxyntic cells, four types of endocrine cells (A-like, ECL, D and EC), brush cells and wandering cells. PAS and Alcian blue reactions for light microscopy suggest a secretion of neutral and acidic mucosubstances in the surface and foveolar epithelium, of neutral mucosubstances only in the neck cells. Periodic acid-thiocarbohydrazide silver proteinate (PA-TCH-SP) reaction for electron microscopy confirms the presence of neutral mucosubstances within the secretory granules of the surface, foveolar and neck epithelial cells. In all these cells, the reaction product is also evident within sacculi and vesicles of the maturing surface of the Golgi apparatus. A positive PA-TCH-SP reaction also occurs on the membrane (and not on the contents) of the Golgi apparatus (maturing surface) and of the secretory granules of the chief cells as well as on the membrane of the Golgi apparatus and of apical vesicles and tubules of the oxyntic cells. In addition, silver granules slightly enhance the electron density of the contents of the secretory granules in the endocrine cells. Morphological and histochemical findings are discussed and compared with results described by others for monogastric mammals.     

鸡中枢淋巴器官肥大细胞的组织化学与形态学

对哺乳动物的,特别是啮齿动物和人类肥大细胞已有了比较深入的研究, 但关于家禽肥大细胞的研究很少.本研究旨在阐明鸡中枢淋巴器官中肥大细胞的组织化学与形态学特征.本研究证实Carnoy 氏液是鸡肥大细胞的优良的固定液,而中性缓冲福尔马林(NBF) 却阻断了大多数肥大细胞的着染力.甲苯胺蓝和阿尔新蓝是鸡肥大细胞的良好的染料,但阿尔新蓝能使更多的肥大细胞着染,虽然其也可使杯状细胞着染.作者的一种新的染色法, 长时间阿尔新蓝染色(LAB-S)可用于NBF固定的组织中肥大细胞的染色,因为其着染的细胞数与Carnoy 氏液固定甲苯胺蓝染色的细胞数无显著差异(P<0.001).在胸腺髓质中见有大量的肥大细胞,而胸腺皮质仅可见个别肥大细胞位于血管周围及小叶间结缔组织中.腔上囊的皮质与髓质中很少见有肥大细胞.肥大细胞有血管周围分布的倾向,但一个有趣的发现是血管内偶尔也有个别肥大细胞.电镜下可见肥大细胞的胞浆颗粒内充满无定形的颗粒状基质,但其电子密度有的较高,有的较低.少数胞浆颗粒内有旋涡状及网状亚微结构.但未见有人类肥大细胞胞浆颗粒内特征性的晶格状和卷轴状的亚微结构,也未见到在绵羊肥大细胞中描述过的特殊亚微结构.     

Die Feinstruktur der Gallenblase und der Gallengänge

Zusammenfassung In den Hauptzellen des menschlichen Gallenblasenepithels (3 Cholesterose-Fälle) wurden Mukosubstanzen lichtmikroskopisch mit Hilfe der PAS- und Alcianblau-Reaktionen, elektronenmikroskopisch unter Anwendung der PA-TCH-Silberproteinat-und Ferrihydrosol-Methoden dargestellt.Die PAS-Reaktion ist im Golgi-Komplex, in den Sekretgranula und auf den Antennulae microvillares positiv, ebenso die Alcianblau-Reaktion (bei pH=1,2) in den Sekretgranula und auf den Antennulae microvillares. Nach Methylierung wird die Alcianblau-Reaktion negativ.Silberpartikel (PA-TCH-Silberproteinat-Methode) lassen sich in Übergangsvesikeln, Golgi-Komplex, Sekretionsgranula, dichten Körpern und Antennulae microvillares nachweisen; dabei zeigt der Golgi-Komplex deutlich eine Polarität. Außerdem ist diese Reaktion in Vesikeln und Tubuli im apikalen Anteil der Zelle auffallend. Wird die TCH-Behandlung unterlassen, so bleibt an den obengenannten Stellen die Reaktion negativ.Eisen-Partikel (Ferrihydrosol-Methode) liegen erst in den innersten Sacculi des Golgi-Komplexes; Sekretionsgranula, dichte Körper, Vesikel und Tubuli im apikalen Anteil der Zelle sowie Antennulae microvillares zeigen ebenfalls eine positive Reaktion, jedoch nicht nach vorausgehender Methylierung der Schnitte.Die Ergebnisse zeigen, daß vermutlich die histochemisch dargestellten Mukosubstanzen saure (sulfatierte) Glykoproteine enthalten.

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On the fine structure of the gall bladder and biliary ducts

Summary In three cases of cholesterosis the localization of mucosubstances in the principal cells of the human gallbladder was studied with the light microscope using the PAS-and the Alcian blue methods, and with the electron microscope applying the PA-TCH-silverproteinate and colloidal iron methods.The Golgi complex was positive only with PAS, whereas secretory granules and antennulae microvillares stained with both PAS and Alcian blue (pH 1.2). After drastic methylation the Alcian blue reaction remained negative.Silver particles (PA-TCH-silverproteinate method) could be observed in the transition elements between rough surfaced endoplasmic reticulum and Golgi complex, Golgi vesicles and saccules, secretory granules, dense bodies and antennulae microvillares. The Golgi complex displayed a distinct polarity. A positive reaction was observed also in vesicles and tubules located at the apex in the cells. After omission of TCH-treatment, a negative reaction in all these components was obtained.In the Golgi complex iron particles (colloidal iron oxide method) could be seen only in the innermost saccules; secretory granules, dense bodies, vesicles and tubules of the apical portion of the cells as well as antennulae microvillares exhibited again a positive reaction, provided that no methylation was performed prior to staining.Our histochemical results indicate that the mucosubstances of the human gall bladder epithelium probably contain acid (sulfated) glycoproteins.

     

The classic Golgi apparatus and vacuoles

The dense vacuoles, considered to be the classic Golgi apparatus in the root meristem ofFagopyrum, were studied by the following methods: 1. Impregnation methods for the demonstration of the Golgi apparatus, 2. cytochemical methods, 3. electron microscopic methods in the light microscope and 4. the electron microscope. A comparison was made with the classic Golgi apparatus in animal cells in the light and electron microscope. Dense vacuoles inFagopyrum and also evidently in other plants, were taken for the classic Golgi apparatus on account of their morphological similarity to the Golgi apparatus in animal cells on impregnation with silver and osmium and their staining preperties with lipoid methods. Dense vacuoles differ from the classic Golgi apparatus in other chemical properties, such as content of phenol substances, etc. No formations were found in animal cells which were similar to dense vacuoles on investigating by electron microscopy. In the electron microscope dense vacuoles have the appearance of derivatives of the normal light vacuoles known in plant cells. They therefore belong to vacuome of plant cell and cannot be analogous to the classic Golgi apparatus in animal cells. Thus the use of the term Golgi apparatus for dense vacuoles is not well founded. A comparison was made of fixation and impregnation used in the light microscope with fixation in the electron microscope. After fixation with permanganate, dense vacuoles have the same shape as after impregnation. After fixation with permanganate, they stain an intense black in the same way as after impregnation with silver and osmium. The form of the vacuoles is dependent on the fixation used. The comparison was made in the light microscope.     

Electron histochemistry of mucosubstances in normal human rectal epithelium

Synopsis The electron microscopic histochemistry of mucosubstances in sigmoidoscopically and microscopically normal rectal biopsies was studied using techniques currently available. The deposition of Alcian Blue and Ruthenium Red and the distribution of Concanavalin A receptors were limited to the epithelial cell borders. Mucosubstances in the fuzzy coat, Golgi apparatus, lysosomes and secretory vesicles were demonstrated by the periodic acid—chromic acid oxidation methods. Glycogen was demonstrated in the epithelium by periodate oxidation methods and the complex cyanide technique. There was little difference in the distribution of mucosubstances in the epithelial cells at any level of the crypts. Phosphotungstic acid staining under controlled conditions gave a similar distribution of mucosubstances to those revealed by the oxidation techniques.     

Ultrastructure of the secretory cells of the submucosal glands in the human maxillary sinus

Tissue samples obtained from the lateral wall of the maxillary sinuses of five patients were examined by light microscopical, histochemical, and ultrastructural techniques. Submucosal glands were tubulo-alveolar mixed glands. The acini consisted of either all serous or all mucous cells, or a mixture of both. Serous granules were stained by toluidine blue, or by hematoxylin and eosin (H and E), but showed little or no reaction with periodic acid-Schiff (PAS) or Alcian blue. Mucous granules were pale in toluidine blue or H and E preparations, and consisted primarily of acid mucosubstances, as demonstrated by their staining reaction with PAS and Alcian blue. At the electron microscope level, the serous granules were either homogeneously dense, or showed a substructure consisting of at least two layers of distinctly different electron-opacity. Typical mucous droplets consisted of a fibrillar network dispersed in a translucent matrix. A second secretory product was present in the mucous cells in the form of elongated, membrane-bounded structures containing numerous parallel filaments, which measured about 55 Å in diameter. The mucous droplets and the filamentous bodies appear to arise from the opposite faces of the Golgi complex in the mucous cells. The filamentous bodies showed a pronounced tendency to fuse with the mucous droplets. All acini were surrounded by a well-defined myoepithelial layer and contained intercellular nerve terminals.     

Lectin-binding pattern in normal human gastric mucosa

Summary Normal human gastric mucosal cells were examined by light and electron microscopy using lectins as a probe. The ABC method was used with biotinylated lectins for light microscopy and HRP-labeled lectins for electron microscopy. The human gastric mucosal cells revealed specific binding patterns for each lectin by light microscopy. Among the lectins tested, in particular, DBA gave a characteristic pattern. It specifically stained the supranuclear region of surface epithelial cells and the perinuclear region of parietal cells. By electron microscopy, the stacked cisternae and the vesicles of the Golgi apparatus of the surface epithelial cells were positive for the DBA staining. These results show that the DBA-positive supranuclear region observed by light microscopy corresponds to the Golgi apparatus. In the parietal cells, DBA, RCA and ConA bound to the intracellular secretory canaliculi which are invaginations of the cell membrane running around the nucleus in the cytoplasm. Therefore, the tubular perinuclear positive region observed by light microscopy corresponds to the membranes of the intracellular secretory canaliculi. In addition, the ConA reagent stained the endoplasmic reticulum, Golgi apparatus, nuclear envelope, and cell membrane of the parietal cell, which explains the diffuse cytoplasmic staining observed at the light microscopic level with this lectin. Lectins have proved to be very useful for the evaluation of in situ cytochemical aspects of the glycoconjugates characteristic to human gastric mucosal cells.     

Lectin-binding pattern in normal human gastric mucosa. A light and electron microscopic study

Normal human gastric mucosal cells were examined by light and electron microscopy using lectins as a probe. The ABC method was used with biotinylated lectins for light microscopy and HRP-labeled lectins for electron microscopy. The human gastric mucosal cells revealed specific binding patterns for each lectin by light microscopy. Among the lectins tested, in particular, DBA gave a characteristic pattern. It specifically stained the supranuclear region of surface epithelial cells and the perinuclear region of parietal cells. By electron microscopy, the stacked cisternae and the vesicles of the Golgi apparatus of the surface epithelial cells were positive for the DBA staining. These results show that the DBA-positive supranuclear region observed by light microscopy corresponds to the Golgi apparatus. In the parietal cells, DBA, RCA and ConA bound to the intracellular secretory canaliculi which are invaginations of the cell membrane running around the nucleus in the cytoplasm. Therefore, the tubular perinuclear positive region observed by light microscopy corresponds to the membranes of the intracellular secretory canaliculi. In addition, the ConA reagent stained the endoplasmic reticulum, Golgi apparatus, nuclear envelope, and cell membrane of the parietal cell, which explains the diffuse cytoplasmic staining observed at the light microscopic level with this lectin. Lectins have proved to be very useful for the evaluation of in situ cytochemical aspects of the glycoconjugates characteristic to human gastric mucosal cells.     

Mucosubstances of rabbit granulocytes studied by means of electron-microscopic radioautography and X-ray microanalysis

Summary Rabbit bone marrow cells have been studied by means of light-and electron-microscopic radioautography and X-ray microanalysis. Carrier free sulfuric acid was used as the radioactive precursor in this experiment. Immature granulocytes showed more active incorporation than mature ones. Silver grains were observed in the Golgi apparatus and granules in three kinds of granulocytes. Electron-microscopically, immature granules showed the incorporation of inorganic sulfate, while mature ones did not. Sulfur was detected in all kinds of granules of the three granulocyte types by X-ray microanalysis. It is concluded that incorporated inorganic sulfur may be utilized for the synthesis of acid glycosaminoglycans and the sulfur detected by X-ray microanalysis may be that contained in the acid glycosaminoglycan. The sulfur detected in the specific granules of the heterophil probably derives from proteins or polypeptides incorporating sulfur containing amino acids.     

Nitric oxide synthase is localized predominantly in the Golgi apparatus and cytoplasmic vesicles of vascular endothelial cells

The localization of nitric oxide synthase (NOS) in vascular endothelial cells of submucosal blood vessels from the guinea-pig ileum was examined using NADPH diaphorase histochemistry at the light microscopic level, and endothelial NOS immunohistochemistry at the light and electron microscopic level. The pattern of staining observed following NADPH diaphorase histochemistry and endothelial NOS immunohistochemistry was identical. Endothelial cells of the arterioles, capillaries and venules showed small patches of intense, perinuclear staining. Under the electron microscope, endothelial NOS immunoreactivity was found predominantly in association with the Golgi apparatus and with the membranes of some vesicles. Small regions of the plasma membrane and the rough endoplasmic reticulum also showed some immunoreactivity. The presence of NOS in the Golgi apparatus and in vesicles raises the possibility that NOS may be exteriorized by endothelial cells, and hence that nitric oxide is synthesized extracellularly.     

Mucosubstances of rabbit granulocytes studied by means of electron-microscopic radioautography and X-ray microanalysis.

Rabbit bone marrow cells have been studied by means of light- and electron-microscopic radioautography and X-ray microanalysis. Carrier free sulfuric acid was used as the radioactive precursor in this experiment. Immature granulocytes showed more active incorporation than mature ones. Silver grains were observed in the Golgi apparatus and granules in three kinds of granulocytes. Electron-microscopically, immature granules showed the incorporation of inorganic sulfate, while mature ones did not. Sulfur was detected in all kinds of granules of the three granulocyte types by X-ray microanalysis. It is concluded that incorporated inorganic sulfur may be utilized for the synthesis of acid glycosaminoglycans and the sulfur detected by X-ray microanalysis may be that contained in the acid glycosaminoglycan. The sulfur detected in the specific granules of the heterophil probably derives from proteins or polypeptides incorporating sulfur containing amino acids.     

Application of rapid freezing followed by freeze-substitution acrolein fixation for cytochemical studies of the rat stomach

Summary A method involving rapid freezing followed by substitution fixation was developed, using acrolein as a fixative. This was then applied to several cytochemical stainings, and showed well preserved and clear cell structures. Membranes were apparently negatively stained and the ultrastructure of mitochondria, rough endoplasmic reticulum and Golgi apparatus was clearly discernible. The mitochondrial and cytoplasmic matrices were stained rather densely compared with routine chemically fixed preparations, implying a good preservation of matrix substrances. Periodic acid-thiocarbohydrazide-silver proteinate staining was applied to the present method. The mucous granules of surface covering epithelial cells indicated fine staining of bipartite structure and the Golgi apparatus of mucous cells showed clear staining differences based on polarity. Postembedding lectin-ferritin and immunocytochemical stainings were applicable to the present preparations and stable stainings of secretory granules were obtained. A low temperature embedding material, Lowicryl K4M, was also examined. The cell preservation of these samples was not as good as those embedded in Epon, but the rough endoplasmic reticulum and Golgi apparatus of chief cells were stained with anti-pepsinogen antibody as were the secretory granules. The present method was also applicable to light microscopy.     

Three dimensional visualization of the Golgi apparatus and endoplasmic reticulum in the subcommissural organ cells with high voltage electron microscopy

Fine structure and stereo-images of the Golgi apparatus and endoplasmic reticulum (ER) in the subcommissural organ (SCO) cells were visualized by the application of zinc-iodide osmium tetroxide (ZIO) impregnation, conventional electron microscopy and high voltage electron microscopy (HVEM). The Golgi apparatus in the SCO cells of rats, gerbils and hamsters consisted of flattened saccules stacked in parallel array. It showed a selective staining toward ZIO mixture and might form a complex network of tubular structures because of the presence of numerous fenestrations in the flattened Golgi saccules. The cytoplasm of the SCO cells in the rat and gerbil was crowded by dilated cisternae of the ER with a few flattened profiles. In the hamster SCO cells, however, the dilated cisternae of the ER were not observed. Flattened cisternae of ER in all species studied showed a positivity for ZIO impregnation and formed a complex tubular network, whereas dilated cisternae of the ER in the rats and gerbils did not show any reactivity. It was thus determined that the observation of thin and thick sections selectively stained with appropriate reagent for defined cellular organelles under conventional electron microscopy and HVEM offered valuable information about three-dimensional organization of the cell. A definite species-specific variation of SCO ultrastructure and cytochemistry was also demonstrated.