scholarly journals AN ELECTRON MICROSCOPE STUDY OF YOLK FORMATION DURING OOGENESIS IN LEBISTES RETICULATUS GUPPYI

1966 ◽  
Vol 28 (2) ◽  
pp. 209-232 ◽  
Author(s):  
Michael J. Droller ◽  
Thomas F. Roth
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Structural Changes ◽  
Extracellular Material ◽  
Yolk Formation ◽  
Selective Uptake ◽  
Lebistes Reticulatus

The present investigation describes the fine structural changes that occur during proteid yolk formation in the developing oocytes of the guppy (Lebistes reticulatus), an ovoviviparous teleost. These changes suggest the operation of a number of different intra- and extraoocyte processes that may account for the synthesis and deposition of the proteid yolk. Early in oogenesis, the egg's Golgi systems proliferate and begin to disclose an electron-opaque content. Numerous 70-mµ diameter vesicles apparently pinch off from the Golgi systems, transport this material through the egg, and probably then fuse to form a crenate, membrane-limited yolk droplet. At the same time, the rough-surfaced endoplasmic reticulum accumulates a flocculent substance that differs in appearance from the Golgi content. Smooth vesicles, presumably derived from the ER, then coalesce to form a second type of intraoocyte yolk droplet. These dissimilar, separately derived droplets subsequently fuse, thus combining the materials that constitute the intraoocyte contribution to the proteid yolk. Somewhat later in development, the egg appears to ingest extracellular material via 75-mµ diameter bristle-coated micropinocytotic pits and vesicles. These structures apparently fuse to form tubules which then coalesce into large yolk droplets. At a later stage, bristle-coated micropinocytotic vesicles of 100 mµ diameter presumably take up a material that is then probably immediately deposited into a second type of proteid yolk droplet. It is postulated that these two different micropinocytotic structures are specifically involved with the selective uptake of dissimilar extracellular proteid materials.

An Electron-Microscope Study of the Cytoplasmic Inclusions in the Neurones of Locusta Migratoria

1962 ◽  
Vol s3-103 (62) ◽  
pp. 147-153
Author(s):  
DOREEN E. ASHHURST ◽  
J. A. CHAPMAN
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Locusta Migratoria ◽  
Cytoplasmic Inclusions ◽  
Double Membrane

The cytoplasmic inclusions of the neurones of adult Locusta migratoria have been examined in the electron microscope. The mitochondria are easily recognized by their cristae and outer double membranes. Electron-dense inclusions, also with an outer double membrane but possessing numerous closely spaced internal lamellae in various orientations, are probably small lipochondria. Larger and more diffuse inclusions comprising crescent-shaped aggregates of loosely packed parallel lamellae and vesicles are present; the possible significance of these larger inclusions is discussed. A system of numerous small vesicles distributed throughout the cytoplasm makes up the endoplasmic reticulum.

The Effects of Calcium on the Ultrastructure of Cox's Orange Apples With Reference to Bitter Pit Disorder

1975 ◽  
Vol 23 (1) ◽  
pp. 55 ◽  
Author(s):  
HK Mahanty ◽  
BA Fineran
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Thin Sections ◽  
Golgi Bodies ◽  
Cool Storage ◽  
Bitter Pit ◽  
Intermediate Results

An electron microscope study on thin sections of epidermal, hypodermal and cortical tissues has been made of calcium-sprayed and unsprayed apples in relation to bitter pit disorder. Golgi bodies, endoplasmic reticulum, mitochondria, chromoplasts, vacuoles and groundplasm were better preserved in sprayed apples during cool storage for up to 2 months than in unsprayed samples. In unsprayed apples these organelles were often drastically changed. The nucleus remained reasonably well preserved in all samples. Apples from trees sprayed only once gave somewhat intermediate results.

scholarly journals ELECTRON MICROSCOPE STUDY OF THE VITELLINE BODY OF SOME SPIDER OOCYTES

1957 ◽  
Vol 3 (2) ◽  
pp. 301-310 ◽  
Author(s):  
J. Roberto Sotelo ◽  
Omar Trujillo-Cenóz
Keyword(s):  
Endoplasmic Reticulum ◽  
Optical Properties ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Central Core ◽  
Composite Body ◽  
Double Membrane ◽  
Peripheral Layer ◽  
Large Numbers

The structure of the vitelline nuclei of Lycosidae and Thomisidae was described as follows: Vitelline nuclei are constituted of two parts: (a) a peripheral layer (vitelline body cortex), and (b) a central core. The vitelline body cortex is demonstrated to be formed by many cisternae of the endoplasmic reticulum among which mitochondria and Golgi elements are intermingled. The central core is made up mainly of a special type of body described under the name of "capsulated body." Capsulated bodies comprise a capsular layer, limited by a membrane, and two central masses called "geminated masses," each one limited by a double membrane. Irregular masses of closely packed vesicles are found in some cases among the capsulated bodies and free vesicles are present in large numbers. The optical properties of the vitelline body cortex compared with the electron microscope findings lead us to the concept that this layer is a "composite body" according to Weiner's theory.

An Electron Microscope Study of Diffusion Assisted Dislocation Processes in Intermetallic Gamma TiAl

1999 ◽  
Vol 589 ◽  
Author(s):  
F. Appel ◽  
U. Lorenz ◽  
M. Oehring
Keyword(s):  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Structural Changes ◽  
Titanium Aluminides ◽  
Elevated Temperatures ◽  
Strength Properties ◽  
Two Phase ◽  
Term Creep ◽  
Dislocation Sources

AbstractThe paper reports an electron microscope study of diffusion controlled deformation mechanisms in two-phase titanium aluminides which apparently cause the degradation of the strength properties at elevated temperatures. Climb velocities were analyzed in terms the critical vacancy supersaturation necessary for the operation of diffusion assisted dislocation sources. Particular emphasis was paid on structural changes occurring during long-term creep, which are apparently associated with dislocation climb.

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