scholarly journals THE FINE STRUCTURE OF THE AXON AND GROWTH CONE OF THE DORSAL ROOT NEUROBLAST OF THE RABBIT EMBRYO

1970 ◽  
Vol 44 (1) ◽  
pp. 62-79 ◽  
Author(s):  
Virginia M. Tennyson
Keyword(s):  
Tissue Culture ◽  
Neural Tube ◽  
Growth Cone ◽  
Dorsal Root ◽  
Matrix Material ◽  
Basal Surface ◽  
Dense Bodies ◽  
Dense Membrane ◽  
Large Numbers ◽  
Rabbit Embryo

The centrally directed neurite of the dorsal root neuroblast has been described from the period of its initial entrance into the neural tube until a well-defined dorsal root is formed. Large numbers of microtubules, channels of agranular reticulum, and clusters of ribosomes are found throughout the length of the early axons. The filopodia of the growth cone appear as long thin processes or as broad flanges of cytoplasm having a finely filamentous matrix material and occasionally small ovoid or elongate vesicles. At first the varicosity is a small expansion of cytoplasm, usually containing channels of agranular reticulum and a few other organelles. The widely dilated cisternae of agranular reticulum frequently found within the growth cone probably correspond to the pinocytotic vacuoles seen in neurites in tissue culture. The varicosities enlarge to form bulbous masses of cytoplasm, which may measure up to 5 µ in width and 13 µ in length. They contain channels of agranular reticulum, microtubules, neurofilaments, mitochondria, heterogeneous dense bodies, and a few clusters of ribosomes. Large ovoid mitochondria having ribonucleoprotein particles in their matrix are common. Dense membrane specializations are found at the basal surface of the neuro-epithelial cell close to the area where the early neurites first enter the neural tube.

scholarly journals THE APPEARANCE OF ACETYLCHOLINESTERASE IN THE DORSAL ROOT NEUROBLAST OF THE RABBIT EMBRYO

1970 ◽  
Vol 46 (1) ◽  
pp. 64-80 ◽  
Author(s):  
Virginia M. Tennyson ◽  
Miro Brzin
Keyword(s):  
Endoplasmic Reticulum ◽  
Enzymatic Activity ◽  
Neural Tube ◽  
Growth Cone ◽  
Golgi Complex ◽  
Dorsal Root ◽  
Ache Activity ◽  
Nerve Roots ◽  
Dual Distribution ◽  
Rabbit Embryo

In the nine day old embryo, acetylcholinesterase (AChE) is found in the reticulum, i.e. the nuclear envelope, endoplasmic reticulum, and Golgi complex, of a few cells in the neural crest. When the neurite first enters the neural tube, reticulum-bound enzyme is present also in the varicosity of the growth cone of the bipolar neuroblast. At later stages, AChE in the neuroblast has a dual distribution; in addition to the reticulum, activity also appears at the axolemmal surface. The axolemmal activity is found initially on the distal portions of axons in the posterior fasciculus and then progressively appears along the nerve roots in a distal to proximal direction. Very little reticulum-bound enzyme is present within the axon proper. After the 13th day the levels of AChE activity in the posterior fasciculus greatly exceed those in the dorsal root or in the ganglion. Enzymatic activity in the dorsal root equals or exceeds that in the posterior fasciculus by day 16, and both areas are considerably more active than the ganglion.

scholarly journals ELECTRON MICROSCOPY OF PLASMA-CELL TUMORS OF THE MOUSE

1961 ◽  
Vol 9 (2) ◽  
pp. 369-381 ◽  
Author(s):  
D. F. Parsons ◽  
M. A. Bender ◽  
E. B. Darden ◽  
Guthrie T. Pratt ◽  
D. L. Lindsley
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Complex Structure ◽  
Granular Body ◽  
Virus Particles ◽  
Culture Cells ◽  
Large Numbers ◽  
Tumor Agent

The X5563 tumor has been grown in tissue culture. Cells similar to those of the original tumor migrated from the explant and attached to the glass walls of the culture vessels. Electron microscopy showed that large numbers of particles, similar in morphology to virus particles, were associated with these cells after 7 days of culture. The two principal types of particles found in the tumor in vivo appear to be present in vitro. Many more of these particles, however, were larger and showed a more complex structure. Whereas the particles were mainly localized inside endoplasmic reticulum or the Golgi zone in the tumors in vivo, in the tissue culture the majority of the particles were associated with the plasma membrane and were found outside of the cells. The relation of the particles to the granular body is discussed as well as a possible relation to the mammary tumor agent.

Neurosecretory granules in the infective stage of Haemonchus contortus

Parasitology ◽  
1968 ◽  
Vol 58 (3) ◽  
pp. 657-662 ◽  
Author(s):  
W. P. Rogers
Keyword(s):  
Technical Assistance ◽  
Public Health Service ◽  
Special Role ◽  
Public Health Service Grant ◽  
Posterior Edge ◽  
Anterior Border ◽  
Dense Bodies ◽  
Large Numbers ◽  
Light Region ◽  
Light Area

Large numbers of electron-dense bodies, 700–1900 Å in diameter, usually seen each with its own limiting membrane, were found in axons of the ventral nerve of infective juveniles of H. contortus. Axons containing these granules merged, without limiting membranes, with a ‘light’, diffusely granular region, about 1·5–2 μm3. The ‘light’ area also merged without boundaries with the underlying cuticle which was different from the surrounding cuticle. This modified cuticle, of which the anterior border lies about 1·3 μm from the posterior edge of the excretory pore, extends slightly beyond the ‘light’ area. Otherwise it is a useful topographical marker for the extent of the ‘light’ area.It is considered that the ‘light’ region has a special role in the physiology of the cuticle.I wish to thank Mrs M. Ross for expert technical assistance and Mr R. I. Sommerville for valuable advice. This work was supported by a U.S. Public Health Service Grant, AI 04093–05. The use of the Siemens electron microscope was made possible by a grant from the Australian Research Grants Committee. Financial help from Parke, Davis and Co. (Australia) is also gratefully acknowledged.

scholarly journals Tissue culture of isolated glomeruli in experimental crescentic glomerulonephritis.

1978 ◽  
Vol 147 (1) ◽  
pp. 98-109 ◽  
Author(s):  
S R Holdsworth ◽  
N M Thomson ◽  
E F Glasgow ◽  
J P Dowling ◽  
R C Atkins
Keyword(s):  
Tissue Culture ◽  
Inflammatory Reaction ◽  
Crescentic Glomerulonephritis ◽  
Mesangial Cells ◽  
Fc Receptors ◽  
Substantial Proportion ◽  
Cell Populations ◽  
Phagocytic Capacity ◽  
Isolated Glomeruli ◽  
Large Numbers

As a means of studying mechanisms of response to injury in glomerulonephritis, glomeruli from normal sheep and rabbits and from sheep and rabbits with experimental crescentic glomerulonephritis have been isolated and grown in tissue culture. The cellular outgrowths from the normal and diseased glomeruli have been compared. The outgrowth of glomeruli from normal animals contained only two cell populations whose microscopic and ultrastructural appearances were of epithelial and mesangial cells. The same cells were also observed in the outgrowths of glomeruli from animals with crescenti nephritis but in addition a third population of cells was present in large numbers. These cells were identified as macrophages by their mobility, ultrastructure, phagocytic capacity, and presence of Fc receptors. Glomerular outgrowth from sheep with crescentic glomerulonephritis contained 170 +/- 20 (SEM) macrophages and outgrowths from rabbits with crescentic nephritis contained 64 +/- 6 (SEM) macrophages per glomerulus. We have previously observed large numbers of macrophages in the outgrowth of isolated glomeruli from humans with rapidly progressive crescentic glomerulonephritis. The predominance of the macrophage in cultures of glomeruli from both human and animal crescentic glomerulonephritis suggests that this is an important cell in the inflammatory reaction occurring in crescentic glomerulonephritis and may comprise a substantial proportion of the cells forming the crescent.

Vegetative propagation of Sitka spruce

1987 ◽  
Vol 93 (1-2) ◽  
pp. 197-203
Author(s):  
Allan John ◽  
Bill Mason
Keyword(s):  
Tissue Culture ◽  
Large Scale ◽  
Sitka Spruce ◽  
Scale Production ◽  
Stem Cuttings ◽  
Culture Techniques ◽  
Commercial Trial ◽  
Large Numbers ◽  
Large Scale Production ◽  
Tissue Culture Techniques

SynopsisA combination of two vegetative techniques is seen as a possibility for large-scale production of juvenile, rooted Sitka spruce cuttings of improved genotype. Tissue culture techniques, under development, would be used to produce large numbers of stock plants for stem cuttings production. Cuttings techniques, currently under commercial trial, would be used to produce the rooted plants for forest establishment.

Mast cell response during the early phase of tuberculosis: an electron-microscopic study

1977 ◽  
Vol 23 (9) ◽  
pp. 1245-1251 ◽  
Author(s):  
Samuel Ratnam ◽  
Shobhitha Ratnam ◽  
B. K. Puri ◽  
Saroj Chandrasekhar
Keyword(s):  
Mast Cell ◽  
Mycobacterium Tuberculosis ◽  
Electron Microscope ◽  
Host Tissue ◽  
Tuberculous Infection ◽  
Electron Microscopic ◽  
Morphological Alterations ◽  
Dense Bodies ◽  
Large Numbers ◽  
Host Tissues

Guinea pig lungs were infected with Mycobacterium tuberculosis by intratracheal route and examined under electron microscope to investigate the morphological alterations of the organisms, if any, and the response of the host tissue. The bacilli showed no changes in their morphology, while the host tissues revealed several cells containing many electron-dense intracytoplasmic granules. These cells were predominantly seen during the 1st week of infection. The electron-dense bodies of these cells may be the ones observed by earlier workers and suggested to be the altered forms of tubercle bacilli. The present investigation, however, revealed them to be the granules of the mast cells. These cells were observed to respond to tuberculous infection during the first few days by appearing in large numbers crowded with intracytoplasmic granules and soon disintegrating as the result of subsequent degranulation. The above observation is presented and its significance discussed.

scholarly journals Characterization of the turning response of dorsal root neurites toward nerve growth factor.

1980 ◽  
Vol 87 (3) ◽  
pp. 546-554 ◽  
Author(s):  
R W Gundersen ◽  
J N Barrett
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Growth Cone ◽  
Dorsal Root ◽  
Growth Cones ◽  
Individual Growth ◽  
Ionophore A23187 ◽  
Nerve Growth ◽  
Neurite Initiation ◽  
Turning Response

This study reports that chick dorsal root ganglion neurites undergo a rapid (20 min) reorientation of their direction of growth in response to nerve growth factor (NGF) concentration gradients in vitro. Dorsal root ganglia from chick embryos were explanted onto a collagen-poly-L-lysine substrate. After 24-48 h in culture, NGF gradients were applied to individual growth cones via a micropipette containing 50 biological units NGF/ml. The growth cones turned and grew toward these NGF sources. This turning response was not caused by the trophic effects of NGF on neurite initiation, survival, or growth rate. Dorsal root neurites also grew toward sources of mono- and dibutyryl cyclic adenosine monophosphate (dB cAMP), cyclic guanosine monophosphate (cGMP), and elevated calcium in the presence of the calcium ionophore A23187. These results are consistent with the hypothesis that intracellular levels of cAMP and /or cGMP and calcium may play a role in the turning response of dorsal root neurites toward NGF, but do not establish a causal relationship between the mechanisms of action of NGF, cyclic nucleotides and calcium. Total growth cone adherence to the substrate was measured using a timed microjet of perfusion medium. NGF increased the adherence of growth cones to the substrate, but caffeine and dB cAMP which also elicit the positive turning response, decreased growth cone adherence. Calcium, which did not elicit the positive turning response, produced a greater growth cone adherence to the substrate than that observed with NGF. Although these results do not rule out a role of adhesion changes in axonal turning to NGF, they show that a general increase in adherence does not correlate well with the rapid turning response observed in this study.

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