scholarly journals AN ELECTRON MICROSCOPIC STUDY OF THE DEVELOPMENT OF SYNAPSES IN CULTURED FETAL MOUSE CEREBRUM CONTINUOUSLY EXPOSED TO XYLOCAINE

1971 ◽  
Vol 49 (2) ◽  
pp. 362-371 ◽  
Author(s):  
Pat G. Model ◽  
Murray B. Bornstein ◽  
Stanley M. Crain ◽  
George D. Pappas
Keyword(s):  
Cerebral Cortex ◽  
Fine Structure ◽  
Electron Microscope ◽  
Impulse Activity ◽  
Morphological Differentiation ◽  
Bioelectric Activity ◽  
Electron Microscopic ◽  
Fetal Mouse ◽  
Electrical Impulse ◽  
Mouse Cerebral Cortex

Explants of fetal mouse cerebral cortex, continuously exposed to the local anesthetic Xylocaine from the time of explantation to the time of fixation, were examined in the electron microscope to determine whether morphologically normal synapses and potentially functional interneuronal synaptic networks can form in the absence of electrical impulse activity. Morphological differentiation of complex synaptic networks proceeds normally, and the drug does not alter the fine structure of the formed synapses. These observations are consonant with the electrophysiological data which show that the potential for complex bioelectric activity can develop in the absence of its expression. The development and maturation of functional synaptic networks, then, is not contingent upon prior electrical impulse activity. These data support the concept that organized neuronal assemblies are formed in forward reference to their ultimate function.

An electron-microscope study of centrioles in differentiating motor neuroblasts

Development ◽  
1968 ◽  
Vol 20 (3) ◽  
pp. 343-354
Author(s):  
Katherine M. Lyser
Keyword(s):  
Nineteenth Century ◽  
Fine Structure ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Morphological Differentiation ◽  
Nerve Cells ◽  
Electron Microscopic ◽  
Mitotic Apparatus ◽  
Mature Neurons

Mature neurons with centrioles were first described at the end of the nineteenth century and have been observed in many animals (see Cajal, 1911; Ariëns Kappers, Huber & Crosby, 1936). As mitosis rarely, if ever, occurs after morphological differentiation of the neuroblast begins, the function of the centrioles in nerve cells posed a problem which has yet to be resolved. Held (1909) described centrosomes in differentiating neuroblasts as being associated with the ‘fibrillogenous zone’, which suggests a role for the centriole in the differentiation of neurofibrils. Recently, electron-microscopic observations have refocused attention on the possibility of morphological and functional association between the centrioles of nerve cells and the fibrillar elements, especially neurotubules, which appear to be similar in fine structure to microtubules of other types of cells and to spindle tubules of the mitotic apparatus.

scholarly journals THE FINE STRUCTURE OF ASTROCYTES IN THE CEREBRAL CORTEX AND THEIR RESPONSE TO FOCAL INJURY PRODUCED BY HEAVY IONIZING PARTICLES

1965 ◽  
Vol 25 (2) ◽  
pp. 141-157 ◽  
Author(s):  
David S. Maxwell ◽  
Lawrence Kruger
Keyword(s):  
Cerebral Cortex ◽  
Fine Structure ◽  
Electron Microscope ◽  
Reactive Astrocytes ◽  
Lipid Bodies ◽  
Particle Irradiation ◽  
Fibrous Astrocytes ◽  
Primitive Forms ◽  
Focal Injury ◽  
Glycogen Particles

Normal and reactive astrocytes in the cerebral cortex of the rat have been studied with the electron microscope following focal alpha particle irradiation. The presence of glycogen and approximately 60-A fibrils identify astrocyte cytoplasm in formalin-perfused tissue. The glycogen particles facilitate the identification of small processes and subpial and perivascular end-feet. Both protoplasmic and fibrous astrocytes contain cytoplasmic fibrils and should be distinguished on the basis of the configuration of their processes and their distribution. Acutely reactive astrocytes are characterized by a marked increase in the number of glycogen granules and mitochondria from the first day after irradiation. These cells later hypertrophy and accumulate lipid bodies and increased numbers of cytoplasmic fibrils. The glial "scar" consists of a greatly expanded volume of astrocyte cytoplasm filled with fibrils and displays no signs of astrocyte death, reversion to primitive forms, or extensive multiplication.

scholarly journals Roles of taurine-mediated tonic GABAA receptor activation in the radial migration of neurons in the fetal mouse cerebral cortex

2014 ◽  
Vol 8 ◽  
Author(s):  
Tomonori Furukawa ◽  
Junko Yamada ◽  
Tenpei Akita ◽  
Yoshitaka Matsushima ◽  
Yuchio Yanagawa ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Gabaa Receptor ◽  
Receptor Activation ◽  
Radial Migration ◽  
Fetal Mouse ◽  
Mouse Cerebral Cortex

FINE STRUCTURE OF NUCLEOLI AND RNA-CONTAINING CHROMOSOME REGIONS OF SALIVARY GLAND CHROMOSOMES OF CHIRONOMIDS AND THEIR INTERRELATIONSHIP

1964 ◽  
Vol 42 (6) ◽  
pp. 1147-1155 ◽  
Author(s):  
V. I. Kalnins ◽  
H. F. Stich ◽  
S. A. Bencosme
Keyword(s):  
Fine Structure ◽  
Salivary Gland ◽  
Electron Microscope ◽  
Light Microscopy ◽  
Messenger Rna ◽  
Balbiani Ring ◽  
Electron Microscopic ◽  
Chironomid Species ◽  
Balbiani Rings ◽  
Chromosome Regions

Electron microscope studies of salivary gland nuclei of four chironomid species have shown that the RNA-containing chromosome regions and associated structures, which by light microscopy exhibit a great variety of structures such as bands, granules, micronucleoli, nucleoli, puffs, and Balbiani rings, consist of only few basic units: pars amorpha, nucleolonema, and Balbiani ring granules. The fine structure of the nucleoli and spherical micronucleoli located at various chromosome regions appears to be identical, consisting of pars amorpha, which contains fibers of varying diameters, and strands of nucleolonema composed of fibers and ribosome-like granules. The arrangement of pars amorpha and nucleolonema of nucleoli and spherical micronucleoli follows a consistent pattern. Chromosome fibers are closely associated with pars amorpha, whereas strands of nucleolonema border only the surfaces of pars amorpha. Balbiani ring granules, which have a diameter of 300 Å to 500 Å and are characterized by a particular structure, accumulate in Balbiani rings, in many chromosome regions, and in nuclear sap. In the Balbiani ring these granules seem to be attached to 100 Å chromosome fibers. They are absent in nucleoli and micronucleoli. The possible correlation between our electron microscopic observations and the present-day concept of ribosomal and messenger RNA production is discussed.

scholarly journals The effect of EDTA, cations, and various buffers on the morphology of erythrocyte membranes: an electron-microscopic study

Blood ◽  
1975 ◽  
Vol 45 (5) ◽  
pp. 709-724 ◽  
Author(s):  
L Pinteric ◽  
JF Manery ◽  
IH Chaudry ◽  
G Madapallimattam
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Ethylenediaminetetraacetic Acid ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Electron Microscopic ◽  
Osmotic Hemolysis ◽  
Ionic Calcium

Abstract Membranes of human erythrocytes were prepared by stepwise osmotic hemolysis in Ca2+-free solutions. Examination with the electron microscope after negative staining showed some short, conelike protuberances on the surface of about 20 percent of the ghosts, while 80 percent were round, intact spheres. After Ca2+ treatment, all membranes were round and intact. After exposure to ethylenediaminetetraacetic acid (EDTA) (1.0 mM, pH 7.4), the entire ghost surface was covered with long, thin extrusions called stromalytic forms (about 460 per cell). Their sizes, shapes, and fine structure are described. Exposure to ionic calcium (1.4 times 10-minus 4M) abolished the EDTA-induced stromalytic forms. A second exposure to EDTA reversed this Ca2+ effect. ATP, like EDTA, produced stromalytic forms. EDTA- induced stromalytic forms were also abolished by Zn2+, La3+, and Nd3+ at concentrations of 1–5 times 10-minus 4 M. Mg2+ at 10-minus 2 M was ineffective. Ghosts were prepared by graded lysis in various buffers. Those prepared in phosphate were the most stable and provided consistent EDTA effects and Ca2+ reversal. Ghosts in Tris-HCl showed breakdown unless salt was added. Moderately satisfactory ghosts were also obtained in Hepes-NaOH buffer and salt.

The effect of EDTA, cations, and various buffers on the morphology of erythrocyte membranes: an electron-microscopic study

Blood ◽  
1975 ◽  
Vol 45 (5) ◽  
pp. 709-724
Author(s):  
L Pinteric ◽  
JF Manery ◽  
IH Chaudry ◽  
G Madapallimattam
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Ethylenediaminetetraacetic Acid ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Electron Microscopic ◽  
Osmotic Hemolysis ◽  
Ionic Calcium

Membranes of human erythrocytes were prepared by stepwise osmotic hemolysis in Ca2+-free solutions. Examination with the electron microscope after negative staining showed some short, conelike protuberances on the surface of about 20 percent of the ghosts, while 80 percent were round, intact spheres. After Ca2+ treatment, all membranes were round and intact. After exposure to ethylenediaminetetraacetic acid (EDTA) (1.0 mM, pH 7.4), the entire ghost surface was covered with long, thin extrusions called stromalytic forms (about 460 per cell). Their sizes, shapes, and fine structure are described. Exposure to ionic calcium (1.4 times 10-minus 4M) abolished the EDTA-induced stromalytic forms. A second exposure to EDTA reversed this Ca2+ effect. ATP, like EDTA, produced stromalytic forms. EDTA- induced stromalytic forms were also abolished by Zn2+, La3+, and Nd3+ at concentrations of 1–5 times 10-minus 4 M. Mg2+ at 10-minus 2 M was ineffective. Ghosts were prepared by graded lysis in various buffers. Those prepared in phosphate were the most stable and provided consistent EDTA effects and Ca2+ reversal. Ghosts in Tris-HCl showed breakdown unless salt was added. Moderately satisfactory ghosts were also obtained in Hepes-NaOH buffer and salt.

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