Inflammation with restricted lysosomal proteolysis during early ascites carcinoma invasion of mouse parietal peritoneum. A medium and high-voltage electron microscopic and cytochemical study

A carcinoma invasion system (Krebs-2 and Ehrlich tetraploid ascites tumors invading mouse peritoneum) was studied by high-voltage electron microscope (HVEM) stereoscopy, conventional (medium voltage) electron microscopy (MVEM), and cytochemistry. Tumor cells entered areas of peritoneum (mainly parietal) only where mesothelial cells were damaged and where there was inflammation of the underlying stroma. The initial invasion was different from that of most other invading carcinomas in that there was minimal breakdown of basal lamina and collagen. Neither tumor cells, inflammatory leukocytes nor peritoneal fibroblasts showed significant secondary lysosome production or release of intracellular or extracellular acid phosphatase. Morphological and cytochemical criteria suggest that in some invading carcinomas, as with non-tumor migrating cells such as leukocytes, widespread proteolysis due to diffusion of proteases is not a prerequisite for invasion of stromal connective tissue.     

An electron microscope study of intrusions into alarm substance cells of the channel catfish

Thin and ultrathin sections of the epidermis of two channel catfish Ictalurus punctatus were studied in light and electron microscopes, respectively, to learn more about intrusions of entire other cell types into alarm substance cells, first noted in 1981. Several degrees of intrusion and several stages in the process of total intrusion are described: microvillus-like projections, pseudopod-like projections, telophase-stage projections, total cell intrusion. In addition, several different cell types intrude: lymphocyte-like cells, general epidermal cells, virus-infected cells and other alarm substance cells. These findings indicate that the alarm substance cell is extraordinarily subject to invasion by other cell types. They suggest that its plasma membrane may have been modified so as to be somewhat less effective in preserving cell integrity (and thus more easily release its alarm pheromone on injury) than is the case with most other cell types or that the alarm substance acts as an attractant for other epidermal cells.     

The chondriome of selected trypanosomatids. A three-dimensional study based on serial thick sections and high voltage electron microscopy

The unitary nature of the chondriome of two species of trypanosomatids, Blastocrithidia culicis and Trypanosoma cruzi, has been demonstrated by utilizing serial thick-sectioning techniques combined with high voltage electron microscopy. Profiles of mitochondrial elements seen in thin sections and suspected to be parts of a continuum were confirmed by serial thick sectioning (0.25-0.50 mum thick) and stereopair analysis to be parts of the same mitochondrion. Three-dimensional models obtained from tracings of mitochondrial profiles on cellulose acetate reveal the mitochondrion of B. culicis to consist of a posterior mass with six tubular extensions extending upward and terminating in the anterior apex. The kinetoplast was found suspended between two of the tubular extensions, or less frequently, protuding as a nodule from one of the extensions. A bifurcation of one of the extensions was found in some specimens. The mitochondrion of T. cruzi consists of a triangular- shaped convoluted tubule, the base being the kinetoplast portion while the apex is directed posteriorly. The mitochondrion bifurcates behind the flagellar pocket, lateral to the kinetoplast, sending two entwined extensions into the tenuous anterior apex. Whether the mitochondrion of T. cruzi is unitary in the trypomastigote form was not determined in this study, since only epimastigote forms were used.     

A scanning electron microscope study of the papilla basilaris of Gekko gecko

Summary The sensory hair cells of the ventral 2/3 of the papilla basilaris of Gekko gecko are divided into anterior (pre-axial) and posterior (post-axial) portions by a mid-axial gap or hiatus where there are no hair cells. There is no separation of the hair cells in the dorsal third of the papilla. There are three tectorial membrane modifications: an attached thickened membrane covering the pre-axial hair cells, sallets covering the post-axial hair cells, and an attached filamentous membrane covering the dorsal hair cells. The number of hair cells is greatest ventrally and decreases dorsally. There are approximately 2000 to 2100 hair cells. The kinocilia of the hair cells of the anterior halves of both the pre- and the post-axial vertical hair-cell rows are oriented posteriorly, while the kinocilia of the posterior halves are oriented anteriorly. The kinocilia of the hair cells of the dorsal third of the papilla are mostly oriented posteriorly. Thus, kinocilial orientation of the ventral 2/3 of the papilla is doubly bidirectional, and the dorsal 1/3, largely unidirectional.I would like to thank Ms. Maria Maglio for her skill in handling the technical aspects of the scanning electron microscopy as well as her artistry in achieving photographic excellence on the scope, David Akers for expert photographic assistance, and Wayne Emery for the drawings. Research sponsored by United States Public Health Service Grant NS-09231.     

Light and electron microscope study of a new species of Thelohania (Microsporida) in the shrimp Pandalus jordani

Thelohania butleri n. sp. was found in cells of skeletal muscles of the shrimp Pandalus jordani, from Queen Charlotte Sound, British Columbia, Canada. Sporulation stages were studied with the light and the electron microscope. Earliest stages were small and apparently uninucleate. Next were small diplokaryotic cells that possibly arose by fusion of the former. These enlarged and underwent sporogony. Sporogony was a series of three binary divisions, each producing unikaryotic cells. There was no sporogonial plasmodium. The spore was ovoid, 4.8 × 3.1 μm (stained), with a large crescentic nucleus and rounded posterior vacuole. The polar filament was isofilar, doubly coiled, with about 10 turns. This species closely resembles the type T. giardi Henneguy. It is concluded that sporogony by means of three binary divisions and lack of a sporogonial plasmodium may be essential characters of the genus Thelohania Henneguy, 1982.     

A light and transmission electron microscope study of hepatic portal tracts in the rhesus monkey (Macacus rhesus)

This study reports on morphological features of hepatic portal tracts in the liver of a rhesus monkey. The light microscope shows that the number of each type of principal component comprising a portal tract varies but that there are usually one to five lymphatics, one bile ductule, one bile duct, one arteriolar and one arterial branch of the hepatic artery, and one hepatic portal vein. Bile ductules, in cross section, have 6-10 cells (mostly low pyramidal, but with a few cuboidal) bordering the lumen, an outside diameter of from about 20 to 25 microm, and a luminal diameter of from 2 to 10 microm. Bile ducts, in cross section, have more than 10 cells (about equal numbers of low pyramidal and cuboidal) bordering the lumen, an outside diameter greater than 25 microm and a luminal diameter of greater than 10 microm. The term "pyramidal" has not previously been applied to the cells of the ductules and ducts. The monkey tracts show several cytological features previously undescribed, viz., abortive cilia and basal bodies in the duct cells, abortive cilia in the ductule cells, and an occasional aggregation of ribosomes in arterial endothelial cells. They also show a major histological feature previously mentioned but not illustrated, viz., bundles of nerve processes which exhibit a preferential location, i.e., proximity to the arterioles and arteries.     

Renal microvasculature in the adult pipid frog,Xenopus laevis: A scanning electron microscope study of vascular corrosion casts

We studied the opisthonephric (mesonephric) kidneys of adult male and female Xenopus laevis using scanning electron microscopy (SEM) of vascular corrosion casts and light microscopy of paraplast embedded tissue sections. Both techniques displayed glomeruli from ventral to mid-dorsal regions of the kidneys with single glomeruli located dorsally close beneath the renal capsule. Glomeruli in general were fed by a single afferent arteriole and drained via a single thinner efferent arteriole into peritubular vessels. Light microscopy and SEM of vascular corrosion casts revealed sphincters at the origins of afferent arterioles, which arose closely, spaced from their parent renal arteries. The second source of renal blood supply via renal portal veins varied interindividually in branching patterns with vessels showing up to five branching orders before they became peritubular vessels. Main trunks and their first- and second-order branches revealed clear longish endothelial cell nuclei imprint patterns oriented parallel to the vessels longitudinal axis, a pattern characteristic for arteries. Peritubular vessels had irregular contours and were never seen as clear cylindrical structures. They ran rather parallel, anastomosed with neighbors and changed into renal venules and veins, which finally emptied into the ventrally located posterior caval vein. A third source of blood supply of the peritubular vessels by straight terminal portions of renal arteries (vasa recta) was not found.     

A combined scanning and transmission electron microscopic study and electron probe microanalysis of human pineal acervuli

Summary Untreated, decalcified and trypsinized acervuli from human pineal bodies were studied with the scanning and transmission electron microscope as well as by electron probe microanalysis. The mulberry-like acervuli are composed of a various number of spherical lobes (135–800 m) between which clustered groups of globuli (4–14 urn in diameter) are observed. The acervular lobes are very probably formed by an aggregation of these globuli. Small round particles 125–500 Å in diameter are observed on the surface of the pineal concretions. These are not influenced by either decalcification or trypsin treatment. The acervular mineral corresponds morphologically to hydroxyapatite. The electron probe microanalysis reveals the existence of calcium and phosphorus as main components of the acervuli. Small quantities of magnesium and strontium were also detected.Dedicated to Professor Berta Scharrer on the occasion of her 70th birthdayWith the technical assistance of Mr. P.A. MilliquetThe author wishes to thank Mr. Bauer and Mr. Fryder (Nestec SA, La Tour de Peilz) for the use of the Cambridge Stereoscan electron microscope and Dr. T. Jalanti (C.M.E., Lausanne) for his help with the use of the X-ray microanalyser     

The digestive tract of the amberjack Seriola dumerili, Risso: a light and scanning electron microscope study

The histology of the digestive tract of the amberjack ( Seriola dumerili , Risso) was studied using light and scanning electron microscopy. The anterior oesophagus mucosa displays primary and secondary folds lined with a stratified squamous epithelium with fingerprint-like microridges which is substituted, on the top of the oesogaster folds, by a simple columnar epithelium with short microvilli. Only primary folds are present in the stomach. The anterior portion is rich in simple tubular glands, whereas the oesogaster and the pyloric region are devoid of them. Pyloric caeca and anterior and middle intestine mucosa display the same pattern of folding. The dominant cell type is the enterocyte, which exhibits larger and thinner microvilli in the caeca than in the intestine. The columnar epithelium of the rectum is replaced, in the anal sphincter, by a stratified flattened epithelium. Goblet cells are numerous throughout the whole length of the tract with the exception of the initial part of the oesophagus, the oesogaster, the stomach and the anal sphincter. Mucosubstances have been shown to vary in the different regions of the gut: acid mucines are found in the oesophagus, pyloric stomach, caeca, intestine and rectum, whereas neutral mucosubstances dominate in the anterior portion of the stomach. The muscularis is well developed throughout the length of the tract: two layers of striated muscle at the oesophageal level; two layers of smooth muscle in the stomach wall and three at the intestinal level.     

A light and electron microscope study on oogenesis in the freshwater pulmonate snail Biomphalaria glabrata

In the freshwater snail Biomphalaria glabrata the formation and composition of yolk granules and the role of the follicle cells were studied by histochemical and electron microscopical techniques. The rough endoplasmic reticulum and the Golgi apparatus appeared to be involved in yolk formation, which is a continuous process throughout oogenesis. From the very beginning of yolk formation two main types of yolk granules were distinguished morphologically. However, with histochemical and enzyme cytochemical methods no differences were observed between these types. The granules acquire lysosomal enzymes after oviposition, indicating that their main function is probably digestion of perivitelline fluid, which contains nutrients for the developing embryo.Yolk formation and the activity of the follicle cells were studied in successive stages of oogenesis by quantitative electron microscopy. The data strongly suggest that the follicle cells are involved in the formation of the follicular cavity and hence in the ovulation process.     

How cells settle on glass: A study by light and scanning electron microscopy of some properties of normal and stimulated macrophages

Summary Some properties of normal and stimulated peritoneal macrophages have been studied using light microscopy, cinemicroscopy, and scanning electron microscopy. No difference in the overall rate of translational movement was found between normal and stimulated cells. Macrophages were found to settle on glass by a process involving initial protrusion of very fine finger-like processes, followed by veils. Full extension occurred sooner in stimulated cells.We are grateful to Professor R. Barer for his criticisms, to Miss Anne Edwards for technical help, to Mr. G. Tuck for help with cinemicroscopy, and to the Science Research Council and the Medical Research Council for grants.     

A study of chemically induced dynamic electron polarization (CIDEP) in Photosystem I of whole algal cells at ambient temperatures

Time-resolved electron paramagnetic resonance (EPR) studies were carried out at room temperature and at 273 K on whole-cell samples of the photosynthetic algae: Anacystis nidulans and Scenedesmus obliquus, the latter being 97% deuterated from the growing medium. These photosynthetic organisms show greatly enhanced EPR signals which result from the generation of nonequilibrium spin populations, a phenomenon known as chemically induced dynamic electron polarization (CIDEP). We report magnetic-field profiles of the early transient signals of Photosystem I which are very similar to those observed at low temperatures. The results suggest that one or more early reduced electron acceptors in Photosystem I are being observed at ambient physiological temperatures.     

Transmission electron microscopy study of the effects of cadmium and copper on fetal rat liver tissue

During the entire period of their pregnancies, three groups of adult pregnant Wistar albino rats were provided with tap water (control; group I) or with tap water containing 10 mg/kg CdCl₂ (group II) or 10 mg/kg CdCl₂ plus 10 mg/kg CuSO₄ (group III). At term, the animals were sacrificed and the fetal livers were removed and examined under electron microscopy. The liver tissue of the fetuses in maternal groups II and III showed degenerative changes to their hepatocytes. In group II, the smooth endoplasmic reticulum tubules showed dilatation, and the mitochondria showed a dense matrix. In group III, some mitochondrial degeneration was also seen, with a diluted matrix and mitochondrial dilatation. There were also more heterochromatic nuclei and an increased number of ribosomes. None of these histopathological changes were present in the fetal liver samples from the maternal group I control animals.     

Culture of cells in beem capsules: A new technique for electron microscopic study of monolayer cultures

Summary A method is described for the monolayer cultivation of primary cell suspensions and established cell lines directly in carbon-coated BEEM capsules. BEEM capsules are routinely employed by electron microscopists in tissue embedding procedures; growing monolayer cultures directly on the lids of inverted BEEM capsules presents the obvious advantage of maintaining cell to cell to substratum contacts with a minimum of stress and damage in the preparative steps for electron microscopy. This work was supported by grant AM 17631 from the National Institute of Arthritis, Metabolism, and Digestive Diseases, grant CA 11339 from the National Cancer Institute. The Jackson Laboratory is fully accredited by the American Association for Accreditation of Laboratory Animal Care.     

Combined immunofluorescence and field emission scanning electron microscope study of plasma membrane-associated organelles in highly vacuolated suspensor cells of white spruce somatic embryos

Highly vacuolated suspensor cells of spruce somatic embryos were examined by immunofluorescence light microscopy using butyl-methyl-methacrylate (BMM) and polyethylene glycol (PEG) embedded sections, transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The use of PEG embedded embryos provided a rapid method for light microscope detection of antigens before committing to FESEM analysis. BMM embedded specimens provided well preserved suspensor cells for immunofluorescence. FESEM permitted high resolution observation of large areas of the inner surface of the plasma membrane and associated cell organelles. Suspensor cells contained mostly transversely oriented cortical microtubules linked to the plasma membrane and adjacent microtubules by cross- bridges. Light and electron microscopy revealed numerous clathrin coated structures on the plasma membrane. These included flat patches of clathrin, coated pits and coated vesicles. Many coated vesicles were associated with microtubules. Both tubular and lamellar endoplasmic reticulum were observed on the plasma membrane by FESEM.     

A scanning electron microscope study of Craspedella sp. from the branchial chamber of redclaw crayfish,Cherax quadricarinatus,from Queensland,Australia

Epidermal topography was examined, including papillate ridges, grooves and ciliated sensory papillae of Craspedella sp. from the branchial chamber of redclaw crayfish, Cherax quadricarinatus, from Queensland, Australia. Rhandites were observed to discharge from ducts opening mainly in a small distal region of the ventral epidermis of the three central (of five) tentacles. These regions, devoid of ciliated sensory papillae, serve to adhere the anterior end of the worms during locomotion. Secretions from glands associated with the posterior attachment organ were observed to discharge from pores on the outside region of the ventral surface of the disc.A comparison of various scanning electron microscopy (SEM) fixation techniques showed that (1) hot fixatives at 90 °C provide most information on the largest number of epidermal structures and (2) different fixation regimes highlight different epidermal features.     

A scanning electron microscope study of the development of free axonal sprouts at the cut ends of dorsal spinal nerve roots in the rat

Summary Rat dorsal spinal nerve roots were cut and the tip on the ganglionic side of the cut was examined by scanning electron microscopy at 0, 7, 20 and 48 h after operation. Seven hours after cutting, free axonal sprouts had started to protrude from the cut end of the nerve. After 20 h the free sprouts were more profuse than at 7 h but were smaller and had a rougher surface. At both 7 and 20 h many of the sprouts consisted of a stalk 2–7 m in diameter with a bulbous end 5–20 m in diameter. A few branching sprouts were seen. At 48 h the sprouts were shrunken with a deeply furrowed surface. The significance of the surface structure of the sprouts is discussed.I.R.D. is supported by the Medical Research Council; P.K. thanks the Mental Health Trust for a project grant     

A transmission electron microscope study using vitrified ice sections of predentin: structural changes in the dentin collagenous matrix prior to mineralization

The assembly of the collagenous organic matrix prior to mineralization is a key step in the formation of bones and teeth. This process was studied in the predentin of continuously forming rat incisors, using unstained vitrified ice sections examined in the transmission electron microscope. Progressing from the odontoblast surface to the mineralization front, the collagen fibrils thicken to ultimately form a dense network, and their repeat D-spacings and banding patterns vary. Using immunolocalization, the most abundant noncollagenous protein in dentin, phosphophoryn, was mapped to the boundaries between the gap and overlap zones along the fibrils nearest the mineralization front. It thus appears that the premineralized collagen matrix undergoes dynamic changes in its structure. These may be mediated by the addition and interaction with the highly anionic noncollagenous proteins associated with collagen. These changes presumably create a collagenous framework that is able to mineralize.