Outgrowth from chick embryo spinal cord in vitro,studied with the scanning electron microscope

Summary Cultures of chick spinal cord have been grown upon a plastic substrate, using the Maximov flying coverslip technique. After fixation, drying and coating in vacuo with carbon and gold, they have been examined with a Cambridge Instrument Company Stereoscan scanning electron microscope. A number of cell types — fibroblasts, oligodendrocytes and astrocytes — have been identified in the outgrowth, and in a single case possibly a neuron. The appearance of these cells as seen with scanning electron microscopy is described. What appear under light microscopic examination to be single processes often possess a multicomponent structure, and are axon bundles rather than single axons. Both bundles and cells are attached to the substrate by discreet finger-like processes. Some relations of glial cells to axon bundles are shown, and appearances suggestive of early myelination are recorded.     

木贼科气孔器的扫描电镜观察

首次用扫描电镜比较观察了木贼科不同生境的问荆(Equisetum arvense L.)、草问荆(E. pratense Ehrhart)、林问荆(E. sylvaticum L.)、水问荆(E. fluviatile L.)、木贼(Hippochaete hyemale L.)等5种植物地上茎气孔器的详细特征,提供了直观的立体图象,并从比较形态学的角度,初步讨论了木贼类的系统学和生态学意义。     

Ultrastructural study of polyspermy during early embryo development in pigs, observed by scanning electron microscope and transmission electron microscope

Polyspermy is generally considered a pathological phenomenon in mammals. Incidence of polyspermy in porcine eggs in vivo is extremely high (30-40%) compared with other species, and polyspermy rate in the in vitro fertilized eggs in pigs can reach 65%. It is still unknown whether polyspermy to a certain degree is a physiological condition in pigs, and whether porcine eggs have any capability with which to remove the accessory sperm in the cytoplasm. The objectives in the present study are to observe the ultrastructural changes of accessory sperm during early embryonic development in pigs. A total of 58 normal, early embryos at one-, two, three-, and four-cell and morular stages were collected from gilts and were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface ultrastructure showed that sperm fusion with the zona pellucida was a continuous process during one-, two-, three-, and four-cell and morular stages, as observed by the SEM. Accessory sperm were present in the cytoplasm of cleaved embryos. The sperm heads in the cytoplasm of cleaved embryos did not decondense. TEM revealed the presence of a condensed sperm head within a lysosome (or phagolysosome) in a three-cell embryo. These observations suggest that polyspermy may be a physiological condition in pigs and that early embryos may develop to term if accessory sperm do not interrupt the embryo genome. Furthermore, lysosome activity could be another physiological mechanism for removing accessory sperm in the cytoplasm of fertilized eggs and cleaved embryos after fertilization in pigs.     

Zinc deficiency in the 11 day rat embryo: a scanning and transmission electron microscope study

Zinc deficient rat embryos were obtained on the 11th day of pregnancy and examined by scanning and transmission electron microscopy. Scanning electron microscopy revealed an increase in the number of deformed embryos, as well as embryonic growth retardation. In addition, the epithelium of zinc deficient embryos displayed a marked increase in surface microvilli, as well as the presence of blebbing. Transmission electron microscopy indicated extensive cell death in the neural epithelium which was apparently more severely damaged by zinc deficiency than were mesenchymal cells. Mitochondrial cristae were affected to a greater degree than any other membrane of the cell and cristael disintigration appeared to represent the principal cellular lesion preceding necrosis of neural cells and neural tube teratology.     

The organization of the mammalian kinetochore: a scanning electron microscope study

Summary A procedure has been developed for scanning electron microscopy that enables the visualization of kinetochores along the surface of isolated chromosomes of the Indian muntjac. Indirect immunofluorescence and thin section analysis of the kinetochores of those isolated chromosomes verified that these structures retained in vivo composition and morphology during the isolation procedure. In scanning electron micrographs the outer surface of the outer kinetochore plate can be visualized as a series of fibers 25–30 nm in diameter that are arranged across the plate. These images are comparable to those obtained by whole mount transmission electron microscopic procedures (Rattner 1986) and are compatible with a model of the kinetochore in which chromatin fiber from the body of the chromosome extend to the outer kinetochore plate.     

Wandering epithelial cells in the rabbit embryo milk line: A preliminary scanning electron microscope study

In order to confirm the previous results obtained during experimental studies on mammary gland organogenesis and elucidate by what means epidermal cells are clustered together into a protruding ridge, the rabbit embryo milk line was examined under the scanning electron microscope. The discovery of wandering epithelial cells strengthens the current hypothesis that cell migration is a fundamental process during milk line morphogenesis.     

Formation of vascular cords in the chick embryo ; scanning electron microscopic observations]

The morphological changes of haemangioblasts during their sorting out from the pleural mesoderm have been studied as well as their later association within vascular cords, using scanning electron microscopy. These transformations involve only changing the shape and the relationship of cells.     

Plant-microbial interaction under gnotobiotic conditions: A scanning electron microscope study

Inoculation of canola seeds withPseudomonas putida GR12-2 stimulates root elongation under gnotobiotic conditions. Transformation ofP. putida GR12-2 with the broad-host-range plasmid pGSS15 abolishes the enhancement of root elongation. With scanning electron microscopy it was found that both transformed and nontransformedP. putida GR12-2 are capable of binding to canola seed coats. In addition, it was observed that 4 days after the initial inoculation the roots of bothP. putida GR12-2- and GR12-2/pGSS15-treated seedlings were free of adhering bacteria despite the fact that it was subsequently shown that both bacterial strains are capable of binding to roots. Thus, adhesion to roots is not necessary for the initial phase of enhanced root elongation that is induced byP. putida GR12-2 under gnotobiotic conditions.     

Scanning electron microscope study of tongue development in the CD-1 mouse fetus

The objective of this study was to examine three dimensionally the embryonic and fetal stages of tongue development with scanning electron microscopy. Time-bred CD-1 mice were sacrificed at quarter-day intervals on days 10-13, and at half-day intervals on days 13.5-16.5 of gestation. Fetal tongues were dissected and fixed in s-collidine buffered 4% glutaraldehyde at pH7.4, and subsequently processed for SEM viewing. Tongue development was initiated on the 11th day by the appearance of the tuberculum impar and the two lateral lingual swellings on arch I. This was followed by the elevation of the hypobranchial eminence, which unites arches III and IV in the ventral midline, and overgrows arch II anteriorly. During the 12th day, remodeling occurred in areas of arches II and III, forming the root of the tongue. A cone-shaped midline swelling, the epiglottis, appeared in the ventral midline of arches III and IV. By the 13th day, the general proportions of the tongue, occupied by the body, root, and epiglottis, were established. The single circumvallate papilla and fungiform papillae were initiated during the early part of the 13th day, followed on the 15th day by differentiation of filiform and foliate papillae and raised nodules of lingual tonsilar tissue. The SEM study documented the temporal and morphological sequence of events during mouse tongue development. The tuberculum impar persisted to the late fetal stages and may therefore contribute largely to the dorsum of the tongue anterior to the circumvallate papilla.     

Morphological observation and characterization of the Pseudoregma bambucicola with the scanning electron microscope

Both leica microscopic camera system and scanning electron microscopy was used to observe and characterize the feet, back, abdomen, antennae and mouthparts of the Pseudoregma bambucicola from the bamboo, Bambusa multiplex. The possible functions of all the external morphological characteristics of the P. bambucicola were described and discussed in detail, which offers a basis for further enriching the biology, phylogeny and ecological niche of the P. bambucicola. Moreover, the morphological results should contribute to morphological identification and differentiation of the P. bambucicola from other aphids in the same family.     

Optical and scanning electron microscopy observation of the mucosa of human fetal tongue

The structural features of the human foetal tongue have been studied in foetuses from 8th to 20th week of pregnancy. The characteristics of the developing papillae as well as of epithelial and mesenchymal layers have been pointed out. An early differentiation of the mesenchymal tissue has been observed, concerning phenomena of cellular condensation and reticular fibers organization both in superficial and deep layers. The hypothesis of the existence of straight interactions between epithelium and mesenchyme also in the developing human tongue mucosa has been suggested. Also the observations at SEM demonstrate that from the 8th to the 20th week the epithelial surface of the tongue reaches a stable structural pattern. From 11th week a characteristic cellular polymorphism occurs: cells with microvilli that diminish progressively, ciliated cells that disappear almost completely at the 20th week and cells whose free surface show microplicae, definitive stage of the tongue cell evolution.     

Cyclic variations of stomatal aperture observed under the scanning electron microscope

Scanning electron micrographs taken from a vertical positionrevealed the stomatal aperture at the central pore and at theouter ledge. Cyclic variations in leaf temperature of tobacco (Nicotianatabacum cv. MC) and sunflower (Helianthus annuus cv. Large Russian)after illumination coincided with the aperture at the centralpore, but did not always at the outer ledge. The relative turgidityof leaf was inversely proportional to the aperture at the outerledge. Moreover, the opening at the central pore was an "8"-shapedaperture provided the opening was small. Thus, the present experimentsindicated the importance in measurement of the stomatal apertureat the central pore for quantitative and qualitative determinationof cyclic variations in the stomatal aperture. (Received October 7, 1977; )