bluuebunny/crossref_metadata_2025 huggingface dataset:
Intercellular Junctions and Cell Contacts in Inverterbrates
Authors: Lane N.J.
Published: June 2020

Invertebrates possess many of the same kind of intercellular junctions as vertebrates although there are frequently structural distinctions between them. Gap junctions, desmosomes and tight junctions are present in invertebrate tissues but their cells may also possess other junctions including the septate, continuous and scalariform types which do not conventionally occur between vertebrate cells. Junctions of the gap, desmosomal and septate variety have been observed in a range of invertebrates including coelenterates such as Hydra (Hand & Gobel, 1972; Filshie & Flower, 1977), molluscs (Flower, 1971; Gilula f. Satir, 1971), "worms' from several phyla (Quick & Johnson, 1977; Flower, 1977) and arthropods including crustaceans (Hudspeth & Revel, 1971; Peracchia, 1973a,b; Lane & Abbott, 1975; Shivers & Chauvin, 1977), chelicerates (Johnson, Herman & Preus, 1973; Lane, 1978a) and insects (Satir & Gilula, 1973; Lane, Skaer & Swales, 1977). However, the intercellular associations known as tight junctions (zonulae occludentes), continuous junctions (zonula continua) and scalariform junctions seem not to occur in invertebrate groups other than the arthropods, at least they have not thus far been reported.
Defect Aggregation and Disordering in Electron Irradiated NiAl
Authors: Liu H. C.
Published: June 2020

Stoichiometric NiAl, which is an ordered B2 superlattice alloy, has been
electron irradiated and observed in-situ in a Hitachi HU-650B high voltage
electron micriscope from room temperature to 450°C. The purpose of this
study is to understand the mobilities and clustering of interstitials and
vacancies, and to investigate order-disorder transformation
mechanism.
High Resolution Side-Entry Goniometer
Authors: Honda T. , Watanabe H. , Ohi K. , Watanabe E. , Kokubo Y.
Published: June 2020

An analytical electron microscope equipped with a side-entry goniometer
(SEG) has recently become more widespread than a conventional electron
microscope by the following reasons: (1) a variety of specimen holders, (2)
large tilting angle with eucentricity. However, the resolution of SEG-system
is about 0.4 nm, whereas the resolution of 0.25 nm or less can be obtained
by an electron microscope equipped with a top-entry goniometer
(TEG)1).

Factors determining the resolution of an electron microscope are (1) the
aberration coefficients of the objective lens, (2) stability of exciting
currents, (3) illumination angle of the electron beam on the specimen, (4)
energy spread of the electron beam, and ( 5) vibration and specimen drift.
It has been usually difficult to observe high resolution images during use
of the SEG system, because of the aberration coefficients of the objective
lens, vibration and specimen drift. In order to obtain a resolution of less
than 0.3 nm with SEG system at 200 kV, both of spherical and chromatic
aberration coefficients should be reduced less than 2 mm. Moreover, relative
amplitude of vibration between the specimen and pole pieces should be less
than a half value of resolution limit. The image drift should be less than
0.02 nm/sec, because the exposure time usually required for photographing a
high resolution image is about 5 second.
Application of the Stem Optimum Imaging Method on a Biological
Macromolecule
Authors: Ohtsuki M. , Crewe A.V.
Published: June 2020

We have used the STEM optimum imaging method in which we employ an
optimum magnification (scan size, D) for given electron probe size (δ). This
can be written as D=420δ (Nyquist rate), when a micrograph is taken at 1024
scan lines [1], Over sampling (D<420δ) or under sampling (D>420δ) in
biological scanning transmission electron microscopy may cause the following
problems: (1) In the case of over sampling, an area of a specimen will be
scanned too many times so that the effects of radiation damage will be
increased; (2) when a micrograph is taken at under sampling conditions, we
may be observing only part of a specimen in which electron probe scans with
an open space between each scan line.

In practice we try to obtain a micrograph with the optimum imaging
conditions (D=420δ) followed by an optical reconstruction procedure using a
low-pass spatial filter. Only spatial frequency information lower than
<(2d)-1 produces the reconstructed image, where
d is the spacing between scan lines. Figure 1 shows the filtering procedure
in which a STEM micrograph of 30 Å-thick amorphous carbon film taken at
D=3700 Å and δ = 8.8Å was used for the illustration. The corresponding
optical diffraction pattern is shown in (b) where the location of the
low-pass filter is indicated. Figure 1(c) shows the reconstructed image of
(a) which consists of the spatial frequency of
<(7.2Å)-1
A Poor Man’s Approach to Semi-Quantitative Analysis with Electron Energy
Loss Spectroscopy
Authors: Isaacson M.
Published: June 2020

In an earlier paper1 it was found that to a good
approximation, the efficiency of collection of electrons that had lost
energy due to an inner shell excitation could be written as

where σE was the total excitation cross-section and
σE(θ, Δ) was the integral cross-section for
scattering within an angle θ and with an energy loss up to an energy Δ from
the excitation edge, EE. We then obtained:

where , with P being the momentum
of the incident electron of velocity v. The parameter r was due to the
assumption that d2σ/dEdΩ∞E−r for
energy loss E. In reference 1 it was assumed that r was a constant.
Extended Core Edge Fine Structure in the E.M.
Authors: Leapman R.D.
Published: June 2020

Extended X-ray Absorption Fine Structure (EXAFS) analysis makes use of
synchrotron radiaion to measure modulations in the absorption coefficient
above core edges and hence to obtain information about local atomic
environments. EXAFS arises when ejected core electrons are backscattered by
surrounding atoms and interfere with the outgoing waves. Recently, interest
has also been shown in using inelastic electron
scattering1-4. Some advantages of Extended
X-ray-edge Energy Loss Fine Structure (EXELFS) are: a) small probes formed
by the analytical electron microscope give spectra from μm to nm sized
areas, compared with mm diameter areas for the X-ray technique, b) EXELFS
can be combined with other techniques such as electron diffraction or high
resolution imaging, and c) EXELFS is sensitive to low Z elements with K
edges from ˜200 eV to ˜ 3000 eV (B to Cl).
“Ultra-Clean” X-Ray Spectra in the Jeol Jem-100cx
Authors: Blake D.F. , Allard L.F. , Peacor D.R. , Bigelow W.C.
Published: June 2020

A number of workers have described instrument modifications designed to
reduce systems peaks obtained in an analytical electron microscope during
EDS analyses (1-4). These procedures, while effective, have suffered from
one or all of the following limitations: 1) the physical modifications to
the column limit the versatility of the instrument in other modes of
operation (for example, low magnification scanning may be prohibited); 2)
hole counts invariably comprise a large enough fraction of the sample
spectrum that they must be subtracted from the spectrum prior to
quantitation; and 3) analysis for elements such as Cu or Fe, which are
present in the near specimen environment, is either impaired or precluded.
We have found that the JEOL JEM-100CX can be modified to produce ultra-clean
X-ray spectra that suffer from none of the above limitations.
Quantitative X-Ray Microanalysis of Ti Alloys
Authors: Rhodes C. G.
Published: June 2020

This paper discusses the results of a systematic study of the effect of
subtransus (below the β/α+β phase boundary) heat treatments on
microstructure and mechanical properties in two α+β titanium alloys.
Quantitative X-ray microanalysis was used to measure the compositions of the
alpha and beta phases in order to evaluate their influence on mechanical
properties.

Ti-6A1-4V and Ti-4.5A1-5Mo-l.5Cr were treated to produce a
microstructure consisting of equiaxed primary alpha-phase grains separated
by a continuous beta phase matrix. The two parameters evaluated in this work
were (1) volume fractions and (2) compositions of the alpha and beta phases.
Measurement of volume fractions was straightforward; however, the
measurement of the compositions of the two phases required development of a
reliable comparative quantitative X-ray microanalytic technique for thin
foil analysis using a conventional transmission electron microscope with
STEM capability. Although our X-ray energy dispersive system included a
typical thin foil computer program, it was not used because of the error
introduced by estimating factors such as foil thickness and phase
density.
Solute Effects in Neutron Irradiated Aluminum
Authors: Sykes L. J. , Hren J. J. , Farrell K.
Published: June 2020

The effects that trace impurities have on the radiation damage
characteristics of aluminum has been studied by Farrell and Houston, (1979).
A large number of aluminum alloys containing 100 ppma of various elements
were neutron irradiated to several fluences and studied by TEM. The results
of this study indicated that copper is a strong suppressor of void swelling
in aluminum. Because of this, the A1 + 100 ppma Cu alloy was chosen for
further analysis of its defect microstructure by the use of the dislocation
loop catalog compiled by the authors (1979). Neutron irradiated pure
aluminum (99.9999%) and A1 + 100 ppma Si were also examined so a standard
for comparison could be achieved (the A1-Si alloy was chosen because of the
transmutation of A1 to Si during neutron irradiation).
Interference Effects in Shadow Image Electron Microscopy (SIEM) and in
STEM and CTEM of Surfaces
Authors: Cowley J. M. , Goodman P. , Turner P.S. , Disko M.
Published: June 2020

It has been reported previously (1,2) that, as a result of the high
degree of coherence of the incident beam a number of novel interference
effects have been seen in shadow images and convergent beam diffraction
patterns formed in the HB-S STEM instrument and observed by means of the
optical analyser system which incorporates an image intensifier and a low
light level TV camera. In this paper we report further new interference
phenomena and the results of more detailed analysis of previously reported
effects.
Defect Structure of Deformed Tungsten Carbide
Authors: Hibbs M.K. , Sinclair R.
Published: June 2020

In an effort to optimize both the hardness and toughness of carbides
used in cemented cutting tools, a project has been undertaken to relate
variations in these mechanical properties to the defect structure of
deformed WC and (W,Ti)C. This paper describes the defects in stoichiometric
WC as revealed by TEM studies. Possible relationships between them and the
atomic configuration and bonding in the material will be discussed.

WC has a hexagonal unit cell with W atoms at the 0,0,0 position and C
atoms at the 1/3,2/3,1/2 position. The c/a ratio is approximately unity with
a=2. 91Å and c=2.84Å. Although the basal plane is the close-packed plane,
the slip plane has been determined by other workers and confirmed by this
study to be {1010}.
Scan Conversion and Noise Reduction Using a Framestore
Authors: Boyes E. D. , Kellar P. R. N. , Goringe M. J. , Dixon-Brown G.
Published: June 2020

Analogue scan conversion has been incorporated into several dedicated
STEM systems1 to produce a composite video signal for
display on a TV monitor, with the image updated at the microscope frame scan
frequency. Greater flexibility is provided by completely digital methods
which have proved particularly useful at relatively slow scan
rates2 and recently an experimental 6-bit intensity
system for a TEM TV camera has been described by
Herrmann3.

This paper reports an experimental adaptation of a commercially
available (Microconsultants) broadcast framstore system to acquire, process
and display images, and potentially also other data, with 8-bit intensity
resolution over a wide range of scan rates. The unit that was adapted for
this purpose is a development of the standard 'Intellect' system which uses
digitally controlled 512x512 sampling of the normal analogue signals at a
rate which can be selected to be suitable for use with either TV or slow
scans of the record type. A simple hardware modification to the input
interface permits intermediate rates such as SEM visual images which have
proved to be the most useful ranges for the initial applications. The
framestore has been interfaced to a JEM100C ASID-4D Temscan and also to an
HVEM TV camera used for recording dynamic experiments. Interfacing to the
SEM control box was straightforward using the display blanking pulses with
50Ω line drivers to synchronise the rates of sampling the line and frame
scans. The original system was designed to accept only inputs to NTSC TV
standards with which the TV camera is directly compatible.
A Charge Coupled Device Readout System for Electron Microscopy
Authors: Downing Kenneth H. , Ho Ming-Hsiu , Glaeser Robert M.
Published: June 2020

We have investigated the possibility of using a charge coupled device
(CCD) as a direct, electron-sensitive readout device for a CTEM.
Two-dimensional imaging CCD's, developed as normal television camera
elements, are semiconductor devices in which an image is formed on an array
of photo-sensitive sites, causing the accumulation of an electric charge
proportional to the incident flux. The video signal is generated by
sequentially transferring the charges for each element of a line, in
bucket-brigade fashion, to the input of the video amplifier. Sensitivity of
the CCD to electrons has been demonstrated by the successful application in
photocathode tubes, where the photoelectrons are accelerated to an energy up
to 15 keV onto the image sensing area of the CCD. The application of the
device in a 100 keV transmission electron microscope (Ferrier and Chapman,
private communication), with the device in vacuo at the image plane, seems
to have promising possibilities for image intensifier, electron counting,
and computer input devices. A CCD readout system should have several
advantages over previously designed video readout systems, including
elimination of the phosphor, fiber optic or lens coupling, and intermediate
image intensifier stages. The high gain and low noise of the device should
allow detection of single electrons with a detective quantum efficiency near
unity.
Electron Microscopy of “Metallic” Polymers
Authors: Geiss R. H.
Published: June 2020

The discovery of polymers displaying metallic properties has been the
subject of a growing amount of research recently. Polymers such as
halogenated polysulphur nitride, (SN)x, doped
polyacetylene, (CH)x, and polypyrrole show room
temperature conductivities of approximately 104,
103 and 102Ω
-1 cm -l, respectively; and
both pristine and halogenated (SN)x show
superconductivity with T ≃ 0.3°K. The 0° - 300°K behavior of conductivity of
these polymers is plotted in Fig. 1 along with the room temperature
conductivities of several common materials given for comparison. Continued
research on these materials is concerned with achieving greater chemical
stability and plasticity.
Fashioning of Semiconductor Circuit Materials Wtih Finely Focused
Electron Beams
Authors: Pease R. F. W.
Published: June 2020

The application of focused, scanned, electron beams to fabricating
integrated circuits (IC’s) has been pursued since IC’s first appeared 20
years ago. Originally such beams were used for cutting (by beam induced
evaporation) patterns in thin film resistive materials (e.g., nichrome).
Finer lines could be defined by coating the film of circuit material with an
electron sensitive polymer (‘resist’), exposing and developing the resist
and then etching the revealed material. Devices and circuits with
controllable feature sizes down to a few tenths of a micron can be made
using such electron 1ithograhy.1,2 (EL). EL is now
widely used in manufacturing chromium-on-glass masks and for the direct
fabrication of devices and circuits. The advantages of EL over
photolithography for the former application are primarily the greater ease
of steering a submicron beam of electrons under computer control and the
relative absence of diffraction (and hence greater depth of focus) of the
electron beam; in device fabrication the high accuracy with which 1 pattern
can be registered with a previously etched pattern appears to be the
outstanding advantage (Fig. 1).
Combined HVTEM and Ebic Studies in EFG Silicon
Authors: Strunk H. , Ast D.G.
Published: June 2020

The structure and electrical activity of defects in thin Si ribbons
prepared by Edge (Defined) Film Growth (EFG) are of current technological
interest because they influence the efficiency of low cost solar cells. In
addition, the material is highly suited for basic studies on the relation
between structure and electrical activity since it contains a high density
of simple defects.
Metastable Precipitation in Laser-Fabricated Nickel Base
Superalloys
Authors: Snow D.B.
Published: June 2020

The rapid solidification of superalloys can produce metastable
microstructures1 with considerable potential for
age hardening and rapid homogenization. A series of nickel base, high
molybdenum alloys have been developed which permit turbine disk fabrication
by the continuous, incremental deposition of laser melted material on a
cylindrical surface (the LAYERGLAZETM
Process)2 These Ni-Al-Mo-X alloys differ from
conventional superalloys in that they will not crack when subjected to the
high thermal stresses imparted by rapid solidification
(~104°C/s) in sequential layers. Further, the
presence of molybdenum strengthens the alloy at temperatures of ≤760°C, by
the inhibition of γ1 (Ni3Al)
coarsening and the precipitation of Ni-Mo intermetallic
compounds.3
Comparison of Dislocation Loop and Precipitate Strain Fields
Authors: Sykes L. J. , Hren J. J.
Published: June 2020

In a study of the radiation damage characteristics of aluminum alloys,
it was found that (100) precipitate platelets occur in an aluminum alloy
containing 100 ppma Cu when subjected to a neutron fluence of 2 x
1024 (corresponding to 0.26 dpa). As a result of
work at the University of Florida concerning the computer simulation of
small defect images, the relationship between the strain field of a defect
and its TEM image was well understood and the differences between images of
these (100) precipitate platelets and those expected for dislocation loops
were quickly recognized. The theoretical and experimental
images of a dislocation
loop in aluminum are compared in Figure 1 to those for the platelet. Note
that the lobes forming the body of this so-called butterfly image are much
stronger for the platelet than the dislocation loop; the wings, on the other
hand, are much weaker.
Detection of Solute Segregation at Grain Boundaries
Authors: Briceno-Valero J. , Gronsky R.
Published: June 2020

Studies of grain boundary segregation in metallurgical systems are
traditionally based upon the premise that grain boundaries are more likely
sites for solute atoms than their surrounding grains. This idea is
manifested in experimnental studies which distinguish the solute
concentration at boundaries from that of grain interiors using various
spectroscopic techniques, including more recently, energy dispersive X-ray
analysis in TEM/STEM instruments. A typical study therefore usually consists
of spot or line scans across a grain boundary plane in order to detect
concentration gradients at the boundary region. It has also been pointed out
that there are rather severe problems in quantitatively determining the
absolute solute concentration within the grain boundary, and data correction
schemes for this situation have been proposed.
Analytical Electron Microscopy of Ferroelectric BaTiO3
Authors: Mecartney M. L. , Sinclair R.
Published: June 2020

Ferroelectric BaTiO3 has been the subject of TEM
investigations since the early 1960’s(1,2). However most attention has been
focussed on the ferroelectric domain structure in single crystals. This
current work involves the analysis of polycrystalline, ferroelectric
BaTiO3 from various commercial sources. This
material is used for high capacitance capacitors because of its high
dielectric constant. Various dopants (Zr and Bi oxides predominantly) must
be added to stabilize the high dielectric constant over a range of
temperatures(3). Impurities such as
Al2O3 and
SiO2 can also be present due to ceramic processing
procedures. An analysis of this material was performed using TEM and energy
dispersive analysis of x-rays (EDAX) in order to understand better the
effects of these dopants and impurities on the structure and chemical
composition of BaTiO3.
An Electron Microscope Study of the Structure of Black Chrome Solar
Absorber Coatings
Authors: Murr L.E. , Inal O.T. , Valayapetre M.
Published: June 2020

The structure of black chrome coatings electrodeposited from a Chromonyx
plating bath has been the subject of intense study for the past five years
on account of the presumed role it plays in promoting solar absorber optical
properties. Three types of microstructures have been envisioned:0.04 μm
Cr203 particle spheres
composing the coating surface with 0.1 μm Cr particles composing the lower
half of the coating next to the substratel; voids and particulate masses
0.05 – 0.3 μm in diameter containing 0.014 μm Cr particles; and layers of
spherical particles 0.06 – 0.09 μm in diameter which agglomerate to form
0.15 – 0.25 μm clusters containing metallic Cr; with the outer (surface)
layer predominantly Cr203 which
increases in Cr content away from the surface, then levels off at some
relatively fixed ratio (Cr/Cr203)
near the substrate. Changes in the optical properties (absorptivity,
cαs, emissivity, εH) have been
observed for differences in bath temperature, current density, composition,
plating time, etc., but the accompanying structural (microstructural)
changes have been very subtle.
ZrO2/Zr Crystallographic Relationships for Some Anodic
Oxides
Authors: Ploc R.A.
Published: June 2020

Several years ago, an attempt to index an electron diffraction pattern
taken from a piece of zirconium dioxide formed at 573 K in oxygen on a piece
of polyerystalline zirconium was reported. Because the mode of oxide
formation was complicated, it was necessary to write the computer program
PATTERN to simulate Selected Area electron Diffraction (SAD)
patterns.

Recently, single crystals of Zr in the [0001] orientation have been
anodized in IN KNO2 in the constant current mode to 20
volts (56 nm in thickness). The metal was electrolytically thinned and
etched away to leave an oxide window amenable to electron diffraction
experiments. Figure 1 shows the result. The oxide is predominantly cubic
with minor amounts of monoclinic αZrO2 and the sharp
spots are due to the metal. The metal/cubic oxide orientational relationship
is given by Figures 2 and 3 while that for the monoclinic oxide phase is
given by Figures 2 and 4. It is stressed that this relationship has been
determined only for the anodic oxidation of the Zr (0001).
The Effects of Methylmercury on the Dorsal Root Spinal Ganglia of the
Rat
Authors: Yip R. K. , Chang L. W.
Published: June 2020

The neurotoxic effects of organic mercury have been well documented (1).
Dorsal root spinal ganglia (DRG) have been shown to be very vulnerable to
the neurotoxic effects of organic mercury (2-4). The relative sensitivity of
DRG neuronal cell body vs. DRG nerve fibers to mercury, however, is still
controversial (3, 4). The present study attempts to provide some
morphological evidence on the fact that the DRG nerve fibers are more
sensitive to methylmercury toxicity than the DRG neuronal bodies.

Young male CD rats (150-200 gm) were orally intubated with
methylmercuric chloride (2 mg/kg body weight) daily. Control rats were given
equal volumes of saline solution. Food and water were given ad libidum. All
the rats were sacrificed when the methylmercury (MeHg)-treated animals
showed signs of intoxication. The rats were perfused with modified
Karnovsky's fixative intracardially. DRG
(L1-L3) and their fibers were
excised. The tissues were post-fixed in 1% buffered osmium tetroxide,
dehydrated in graded ethanols and embedded in Epon-Araldite for transmission
microscopy. Semi-thick plastic sections were stained with toluidine blue for
bright field light microscopy. Selected areas of the blocks were thin
sectioned. These sections were stained with uranyl acetate and Sato's lead
citrate and examined under a Phillips 201 electron microscope.
Ultrastructural Observations of Endometrial Hyaline Accumulation in
Diethylstilbestrol-Treated Mice
Authors: Wordinger R. , Highman B. , Townsend J. , Greenman D.
Published: June 2020

Several uterine lesions have been correlated with continuous estrogen
exposure. Accumulation of a hyaline-like material has been described by
light microscopy (1,2,3). The objective of this study was to describe the
ultrastructure of this lesion in the mouse.

All mice were of the BALB/cStCrl fC3H/Nctr strain and were
specific-pathogen-free produced from cesarean-derived parentage.
Experimental animals were fed diets containing 320 or 640 parts per billion
(ppb) diethylsti 1 bestrol (DES) dissolved in 95% ethanol and mixed in the
feed. Control animals received the same feed, but without DES. Five animals
from each experimental group, were sacrificed by ether overdose when
moribund, and ranged in age from 622 to 782 days. Tissues were fixed in
cacodylate-buffered 4% glutaraldehyde, post-fixed in 1% osmium tetroxide,
dehydrated in ethanol, embedded in Epon-Araldite, sectioned at 100 nm,
stained with uranyl acetate and lead citrate, and examined with a Philips
EM201 electron microscope. Tissues from 5 control animals were processed in
the same manner.
Electron Microscopic Study of Desquamative Interstitial Pneumonia
Authors: Sud B. N.
Published: June 2020

Lung biopsy of eleven year old girl with clinical diagnosis of bilateral
pneumonia was studied by light microscopy and interpreted as chronic
interstitial pneumonia with macrophages in alveoli (1). A portion of the
biopsy was processed for ultra-structural pathology.

The alveoli either appeared distended or relatively collapsed. In the
former,the type II cells revealed hyperactivity in the formation of
multilamellar bodies from multivesicular bodies (3). Alveolar macrophages
full of prominent lipid glogules (foamy macrophages) were of common
occurrence (Fig.1). Many alveoli had desquamating type II cells,showing
conversion of multilamellar bodies into homogeneous lipid globules,
suggesting their transformation into foamy alveolar macrophages. Mycoplasma
pneumoniae organisms were detected in multilamellar bodies (Fig. 2).
Interalveolar walls were thickened and showed fibrosis and infiltration with
neutrophils.
Electron Microscopy of the Morphology and Extrapulmonary Manifestations
of the Bacterium of Legionnaires' Disease
Authors: Watson John H. L. , Sun C.N. , White H.J.
Published: June 2020

This is a brief report of continuing investigations by SEM and
TEM1, 2, 3 of the morphology and possible
extrapulmonary sites in situ of the Legionnaires' disease bacterium of
proposed genus and species Legionella pneumophila.4
Tissue from lung, heart, spleen, lymph nodes, kidney and liver have been
thoroughly searched for the bacterium in situ, taken at autopsy from a
patient who died of the disease confirmed as Legionnaires' by specific
fluorescent antibody and silver impregnation staining.
Adrenergic Regulation of “Synaptic” Ribbon Populations in the Rat
Pinealocyte
Authors: King T. S. , Holt T. M. , Dougherty W. J.
Published: June 2020

“Synaptic” ribbons (SR) are functionally enigmatic organelles
characteristic of a number of neuroreceptor cells including the mammalian
pinealocyte. SR appear to be responsive to a number of physiological
stimuli, both normal and experimental. During the first days after birth, an
initial, non-rhythmic rise in SR numbers nocturnally and diurnally (King and
Dougherty, 1980) appeared to reflect a similar non-rhythmic increase in
norepinephrine (NE) content in the neonatal rat (Moore and Smith, 1969).
During the second postnatal week, both SR numbers (fig. 1) and NE content
developed circadian rhythms, being high nocturnally and low diurnally. Our
observations suggested that the circadian rhythm in SR numbers is regulated
or influenced directly by an adrenergic mechanism via the superior cervical
ganglia.

Morphometric analyses of SR populations in female rat pinealocytes were
performed to determine changes related to (1) continuous light, (2)
continuous darkness, (3) isoproterenol, isoproterenol-propranolol and
isoproterenol-phentolamine administration and (4) bilateral superior
cervical ganglionectomy (SCGx) and SCGx-isoproterenol administration.
Comparison of this data to that obtained from SR populations during the
course of so-called “normal” 12 hours light:12 hours darkness cycles was
made (fig. 2).
Anhydrous Sectioning of Labile Mitochondrial Inclusions for Analytical
Electron Microscopy
Authors: Hagler H. K. , Lopez L.E. , Murphy M.E. , Buja L.M.
Published: June 2020

The role of calcium influx and its influence on irreversible cell damage
is an important area of interest from a pathophysiological point of view.
Analytical electron microscopy has been used to identify the composition of
mitochondrial inclusions associated with late damage after 24 hours of
ischemia (1). Conventional aldehyde fixation and plastic embedding have been
successful in preserving the insoluble, hydroxyapatite-1ike calcium
phosphate inclusions formed after this period of time because they are
relatively insoluble in aqueous media. This is not the case with early
calcification which appears in the canine temporary myocardial ischemia
model after 40 minutes of coronary artery occlusion followed by 20 minutes
of reflow. These inclusions are poorly preserved by aldehyde fixation but
have been shown to be adequately preserved by ethanol fixation followed by
plastic embedding (1). In this previous work, even though anhydrous fixation
methods were used, the tissue was sectioned on water. This resulted in the
appearance of holes in the mitochondria with relatively few intact granules
left, as shown in Figures 1 and 2. The technique of sectioning anhydrously
on glycerol has recently been implemented to determine the effect of
anhydrous sectioning on the preservation of these early mitochondrial
inclusions. When the same tissue shown in Figures 1 and 2 is sectioned on
glycerol, the mitochondrial granules remain in situ as shown in Figure 3.
There was no loss of granules with the resuTTant holes in the sections.
Glycerol sectioning is performed at a cutting speed of .1 mm/second or less
and the sections are relaxed by heating with a heat probe. The sectioning is
fairly tedious but much less so than ultracryomicrotomy. Typical x-ray
spectra of mitochondrial inclusions from water-sectioned and
glycerol-sectioned tissue are shown in Figure 4. The spectra from
water-sectioned tissue were collected only from those granules which
remained in the tissue as shown in Figure 2. The peak-to-continuum ratio for
the Ca peak of inclusions cut on glycerol was 2.2 while the Ca
peak-to-continuum ratio for inclusions cut on water was 1.1. This
demonstrates that, of the granules analyzed, approximately 50% calcium loss
occurs when the tissue is cut on water.
Observation of Fast Sedimenting, Replicating Bacteriophage T7 DNA by
Negative Staining
Authors: Serwer P.
Published: June 2020

To package the DNA of bacteriophage T7, a preformed, DNA-free capsid
(capsid I) with an envelope thicker than the envelope of bacteriophage
T7:(a) binds DNA, (b) converts to a capsid (capsid II) with a
bacteriophage-like envelope prior to packaging DNA and (c) draws in DNA (1).
During attempts to understand T7 DNA packaging, complexes of capsids with
mature T7 DNA and complexes of capsids with longer than mature, linear T7
DNA have been isolated (2). Objects with capsid-like dimensions were
observed on a fast sedimenting, replicating complex of T7 DNA
(100S+ DNA) prepared for electron microscopy using
a protein monolayer-shadowing technique (3). This procedure for preparation
of specimens does not, however, reveal sufficient detail to rigorously
identify an object as a capsid. To better visualize objects bound to
100S+ T7 DNA, this DNA has been prepared for
electron microscopy using the aqueous technique for the negative staining of
capsid-DNA complexes more recently described (4) (the DNA is coated with
cytochrome c and is revealed in an extended configuration).
Role of the Small (40S) Subunits in the Structure of the Interface of
Eukaryotic Ribosomes
Authors: Boublik M. , Robakis N. , Hellmann W. , Jenkins F.
Published: June 2020

Ribosomes are ribonucleoprotein particles which process the genetic
information coded in mRNA into protein synthesis. The analogy in function
and composition of ribosomes from various sources, both prokaryotic and
eukaryo-tic, imply a structural similarity. At present, high resolution
electron microscopy is the most direct technique with a potential to resolve
the extent of the structural homology of ribosomal particles at a
macromolecular level.

The structure of ribosomes is highly complex as a result of the large
number of their constituents. In general, 80S eukaryotic monosomes consist
of two uneven subunits - large (60S) and small (40S) - accomodating four
different RNAs and approximately 80 different proteins. Mutual orientation
of both subunits on the monosome is of particular interest because it
determines the interface, the supposed site of interactions of ribosomes
with other macro-molecules involved in peptide bond formation. Since
entrapping of the contrasting solution (0.5% aqueous uranyl acetate)
obscures all structural details in the interface, information on its
architecture is limited to an indirect reconstruction based on the
established 3-D structure of both sub-units and their mutual position after
association.
The Golgi Apparatus in Development of the Mesoglea in Sertularia Pumila
(Hydromedusae) Hydranths
Authors: Taatjes Douglas J.
Published: June 2020

The early stages of development of the hydranth of Sertularia pumila is
composed of an outer ectoderm and an inner gastroderm. These tissues are
separated by an acellular middle lamella or mesoglea (1). The ectoderm is a
columnar epithelium, with each cell having a centrally located nucleus (Fig.
1). In mature hydranths the ectoderm has secretory cells facing an outer
chitinous hydrotheca and also stores sensory cells. The gastroderm is made
of highly vacuolated cells which function in digestion. The ectodermal and
gastrodermal cells are elongated with large vacuoles traversed by channels
of cytoplasm which anchor the cells to the mesoglea (Fig. 1)
Silicon Substitution for Calcium in the Shell of the Fingernail Clam,
Musculium Transversum Studied By X-Ray Analysis
Authors: Murphy Judith A. , Paparo Anthony , Sparks Richard
Published: June 2020

Fingernail clams (Muscu1ium transversum) are dominant bottom-dwelling
animals in some waters of the midwest U.S. These organisms are key links in
food chains leading from nutrients in water and mud to fish and ducks which
are utilized by man. In the mid-1950’s, fingernail clams disappeared from a
100-mile section of the Illinois R., a tributary of the Mississippi R. Some
factor(s) in the river and/or sediment currently prevent clams from
recolonizing areas where they were formerly abundant. Recently, clams
developed shell deformities and died without reproducing. The greatest
mortality and highest incidence of shell deformities appeared in test
chambers containing the highest proportion of river water to well water. The
molluscan shell consists of CaCO3, and the tissue
concerned in its secretion is the mantle. The source of the carbonate is
probably from metabolic CO2 and the maintenance of
ionized Ca concentration in the mantle is controlled by carbonic anhydrase.
The Ca is stored in extracellular concentric spherical granules(0.6-5.5μm)
which represent a large amount of inertCa in the mantle. The purpose of this
investigation was to examine the role of raw river water and well water on
shell formation in the fingernail clam.
The Outer Dynein Arms from Sea Urchin Sperm Flagella
Authors: Sale W. S. , Tang W.-J. Y. , Gibbons I. R.
Published: June 2020

A wide variety of experimental evidence now indicates that the bending waves of cilia and flagella are the result of coordinated, localized slid¬ing movements between doublet microtubules of the axoneme (Satir, 1968; Summers and Gibbons, 1971; Shingyoji, et al. 1977; Sale and Satir, 1977). These sliding movements are thought to occur as the consequence of a mecha¬nism in which the dynein arms on each doublet microtubule make and break cross-bridge attachments to the B-subfiber of the adjacent doublet micro¬tubule in a cyclic process involving the binding and hydrolysis of ATP (Summers and Gibbons, 1973; Gibbons and Gibbons, 1973; 1974). The structu¬ral and chemical steps of this cross-bridge cycle are only beginning to be understood (Warner, 1978; Penningroth and Witman, 1979; Sale and Gibbons, 1979; Okuno, 1979). Further understanding of the nature of the events of energy transduction will require knowledge of the composition and structure of the dynein arms.
A Cryo-Transfer System for a Transmission Microscope
Authors: Hax W.M.A. , Lichtenegger S.
Published: June 2020

The crucial step in the preparation of biological specimens is the
fixation procedure intended to preserve the momentary biochemical,
physiological and ultramorphological state of the tissue, despite any
subsequent treatment.

In principle, biological material can be fixed in a chemical or physical
way. It is well known that application of chemical fixatives followed by
conventional resin embedding techniques can cause modifications or obvious
disruption of fine structure or even loss of some cell components. This
conventional procedure may also cause loss or displacement of elements at
any stage in the preparation process. This means that microanalysis, at
least of diffusible substances, is not significant (1). Last but not least,
it should be emphasized that chemical fixation causes all normal functions
to be irreversibly destroyed from the very beginning of the preparation
procedure. Physical fixation means rapid freezing of the biological sample.
It has been amply demonstrated that freezing, when performed correctly, is a
real alternative to ensure artefact-free fixation of living tissue. This is
mainly due to the fact that the aqueous environment of the biological sample
is not disturbed when the sample is frozen. One of the main reasons why
frozen hydrated specimens are not normally directly observed in the electron
microscope, is the technical difficulty of transferring the frozen hydrated
specimen to the specimen chamber and to keep it at low temperature during
observation. This results in loss of the primary advantage of freezing since
the frozen water has to be removed from the specimen before it can be
introduced into the electron microscope.
Distribution of Filipin in Skeletal Muscle Membranes
Authors: Sommer J.R. , Dolber P.C , Wallace N.R.
Published: June 2020

Filipin, a polyene antibiotic, forms complexes (FC) with cholesterol-like substances (1,2). These complexes were visible by EM as "caveolae" either in clusters or singly (cf.Figs.1,3). They covered the entire plasmalemma, including the transverse tubules (TT) and were present in some mitochondria, at the edges of lipid droplets, and in the sarcoplasmic reticulum (SR).In the SR they were found mainly in the intermediate cisternae (IC),chiefIy in the form of clusters (Fig.3) which were often in register with N lines. FCs were significantly less common in the junctional SR and free SR, where, as in the plasmalemma, they were more likely to be in the single form (Fig.2A). This distribution varied somewhat from fiber to fiber, but not within a sin-gle fiber, nor within 1 or 4 hrs exposure to Filipin.
Freeze-Fracture Examination of Tight Junctions of Human Eccrine Sweat
Glands
Authors: Briggman J. V. , Bigelow J. , Bank H. , Spicer S. S.
Published: June 2020

The prevalence of strands shown by freeze-fracture in the zonula
occludens of junctional complexes is thought to correspond closely with the
transepi-thelial electrical resistance and with the tightness of the
junction and its obstruction to paracellular flow.1 The complexity of the
network of junc¬tional complex strands does not appear invariably related to
the degree of tightness of the junction, however, as rabbit ileal junctions
have a complex network of strands and are permeable to lanthanum. In human
eccrine sweat glands the extent of paracellular relative to transcellular
flow remains unknown, both for secretion of the isotonic precursor fluid by
the coil and for resorption of a hypertonic solution by the duct. The
studies reported here undertook, therefore, to determine with the
freeze-fracture technique the complexity of the network of ridges in the
junctional complexes between cells in the secretory coil and the sweat
ducts. Glands from a patient with cystic fibrosis were also examined because
an alteration in junctional strands could underlie the decreased Na+
resorption by sweat ducts in this disease. Freeze-fracture replicas were
prepared by standard procedures on isolated coil and duct segments of human
sweat glands. Junctional complexes between clear cells, between dark cells
and between clear and dark cells on the main lumen, and between clear cells
on intercellular canaliculi of the coil con¬tained abundant anastomosing
closely spaced strands averaging 6.4 + 0.7 (mean + SE) and 9.0 +0.5 (Fig. 1)
per complex, respectively. Thus, the junctions in the intercellular
canaliculi of the coil appeared comparable in complexity to those of tight
epithlia. Occasional junctions exhibited, in addition, 2 to 5 widely spaced
anastomosing strands in a very close network basal to the compact network.
The fewer junctional complexes observed thus far between the superficial
duct cells consisted on the average of 6 strands arranged in a close network
and 1 to 4 underlying strands that lay widely separated from one another
(Fig. 2). The duct epitelium would, thus, be judged slightly more "leaky"
than the coil. Infrequent junctional complexes observed to date in the
secretory coil segment of a cystic fibrosis specimen disclosed rela¬tively
few closely crowded strands.
The Osmotic Effect of Glutaraldehyde Fixative Components
Authors: Tobin Terry P.
Published: June 2020

It is generally accepted that in glutaraldehyde fixation the osmolarity
of the fixative solution is an important consideration in minimizing changes
in the size and morphology of cells and tissue. The results of a number of
studies1,2,3 indicate that glutaraldehyde (GTA) per
se contributes little, If anything, to the effective osmotic pressure of a
GTA fixative and that the fixative vehicle alone must be isotonic to the
tissue to reduce artifacts. This raises a question about the composition of
the fixative vehicle: does an electrolytic (phosphate) buffer assert
different pressures than an electro-lytic buffer plus additives (i.e.,
phosphate plus sucrose). To examine this, the concentration of buffer and
sucrose are altered while the total vehicle osmolarity and GTA concentration
remains constant. To eliminate diffusion barriers, suspended red blood cells
(RBCs) are used as an osmotically sensi-tive system to monitor osmotic
pressures. Furthermore, RBCs possess suffi-cient contrast and dimension to
permit direct visualization with the light microscope and thus it is
possible to circumvent indeterminant artifacts of subsequent processing for
TEM and SEM.
Comparative Advantages of Different Fixatives Suitable for
Freeze-Substitution Fixation.
Authors: Handley Dean A. , Vallespir Steven R.
Published: June 2020

Rapid freezing followed by freeze-substitution (cryofixation) is a
useful method for preserving biological samples for thin section studies. As
such, cryofixation parallels the objectives of conventional fixation. While
there are many fixatives suitable for conventional studies, the usefulness
of different fixatives in conjuncture with the freeze-substitution regime
has not been examined. Although OsOjt is often used in the
freeze-substitution (J.), it is expensive and limited in reactivity towards
cell protein structures. We investigated different fixatives suitable for
freeze-substitution, as they affect overall membrane structure and electron
density. The effectiveness of several acetone-soluble fixatives was judged
by the comparing resulting freeze substitution ultrastructure of rapidly
frozen Bacillus licheniformis 749/c.
In Situ Embedding of Cell Monolayers on Untreated Glass Surfaces for
Vertical and Horizontal Ultramicrotomy.
Authors: Chien Kai
Published: June 2020

Untreated glass is the ideal supporting substrate for cell cul¬ture
growth since it is extremely flat and smooth, transparent and insoluable in
organic solvent. However, difficulties have been encountered in removing
polymerized epoxy resin from a glass surface following in situ cell
monolayer embedment. Vari¬ous techniques have been made to grow cell
cultures on either coated glass surfaces or plastic substrates. The purpose
of this abstract is to describe a heat separation technique which when used
together with a newly designed embedding mold allows cell monolayers to be
transferred from untreated coverglass or glass slide to pre-shaped tissue
blocks. The resulting tissue block can be easily separated and used directly
for orientation light microscopy prior to ultramicrotomy.
Ultrathin Sectioning of Fixed but Unembedded Tissue
Authors: Pease Daniel C.
Published: June 2020

This is intended as a progress report to demonstrate that it is feasible
within limits to section unembedded, glutaraldehyde-fixed tissue thinly
enough for transmission electron microscopy. Much cytological detail will be
preserved. The work has been predicated upon a demonstration of J.L. Farrant
and J.D. McLean1 that x-linking concentrated serum
albumin gel with glutaraldehyde can produce an adequate support for
sectioning small biological objects such as erythrocytes, small algae,
bacteria, and mitochondria. Subsequently, G.L.
Nicolson2 utilized the same technique to obtain
interesting sections of isolated chloroplasts. These experiments suggested
to me that the proteins of the cytosol of many cell types might also be
adequately x-linked with glutaraldehyde to permit ultrathin sectioning if
the specimens could otherwise be suitably supported.
Lectin-Induced RBC Agglutination: Chemical vs. Cryofixation
Authors: Handley Dean A. , Sung Lanping A. , Chien Shu
Published: June 2020

RBC agglutination by lectins represents an interactive balance between
the attractive (bridging) force due to lectin binding on cell surfaces and
disaggregating forces, such as membrane stiffness and electrostatic charge
repulsion (1). During agglutination, critical geometric parameters of cell
contour and intercellular distance reflect the magnitude of these
interactive forces and the size of the bridging macromolecule (2). Valid
ultrastructural measurements of these geometric parameters from agglutinated
RBC's require preservation with minimal cell distortion. As chemical
fixation may adversely influence RBC geometric properties (3), we used
chemical fixation and cryofixation (rapid freezing followed by
freeze-substitution) as a comparative approach to examine these parameters
from RBC agglutinated with Ulex I lectin.
Cell Shape Related Ultrastructural Changes of Monkey Luteal Cells in
Culture
Authors: Gulyas Bela J.
Published: June 2020

The cellular processes that participate either in the maintenance or the
danise of the corpus luteum of the menstrual cycle are incompletely
under¬stood. Maintaining dissociated luteal cells in culture enabled us to
study some of these regulatory mechanisms in the absence of the complex in
vivo milieu. Here, we report SEM and TEM observations on cell shape related
cytoplasmic changes of monkey luteal cells maintained in culture.

The CL were obtained at mid luteal phase of the menstrual cycle of
rhesus monkeys and were dissociated in col1agenase. Dispersed luteal cells
were cultured in Costar dishes, with or without cover glass. The culture
medium, Ham's FlO and 10% fetal calf serum, was supplemented with 100 ng/ml
hCG in half of the cultures.