A stereological study of developmental changes in hepatocyte ultrastructure of zebrafish ( Danio rerio )

2020 ◽  
Vol 236 (6) ◽  
pp. 996-1003
Author(s):  
Katarzyna Anna Zielińska ◽  
Maura Grealy ◽  
Peter Dockery
Keyword(s):  
Danio Rerio ◽  
Developmental Changes ◽  
Hepatocyte Ultrastructure

Microtubule arrays of the zebrafish yolk cell: organization and function during epiboly

Development ◽  
1994 ◽  
Vol 120 (9) ◽  
pp. 2443-2455 ◽  
Author(s):  
L. Solnica-Krezel ◽  
W. Driever
Keyword(s):  
Danio Rerio ◽  
Developmental Changes ◽  
Microtubule Network ◽  
Cell Stage ◽  
Yolk Syncytial Layer ◽  
Animal Pole ◽  
Yolk Cell ◽  
Vegetal Pole ◽  
Cell Organization ◽  
And Function

In zebrafish (Danio rerio), meroblastic cleavages generate an embryo in which blastomeres cover the animal pole of a large yolk cell. At the 500–1000 cell stage, the marginal blastomeres fuse with the yolk cell forming the yolk syncytial layer. During epiboly the blastoderm and the yolk syncytial layer spread toward the vegetal pole. We have studied developmental changes in organization and function during epiboly of two distinct microtubule arrays located in the cortical cytoplasm of the yolk cell. In the anuclear yolk cytoplasmic layer, an array of microtubules extends along the animal-vegetal axis to the vegetal pole. In the early blastula the yolk cytoplasmic layer microtubules appear to originate from the marginal blastomeres. Once formed, the yolk syncytial layer exhibits its own network of intercrossing mitotic or interphase microtubules. The microtubules of the yolk cytoplasmic layer emanate from the microtubule network of the syncytial layer. At the onset of epiboly, the external yolk syncytial layer narrows, the syncytial nuclei become tightly packed and the network of intercrossing microtubules surrounding them becomes denser. Soon after, there is a vegetal expansion of the blastoderm and of the yolk syncytial layer with its network of intercrossing microtubules. Concomitantly, the yolk cytoplasmic layer diminishes and its set of animal-vegetal microtubules becomes shorter. We investigated the involvement of microtubules in epiboly using the microtubule depolymerizing agent nocodazole and a stabilizing agent taxol. In embryos treated with nocodazole, microtubules were absent and epibolic movements of the yolk syncytial nuclei were blocked. In contrast, the vegetal expansion of the enveloping layer and deep cells was only partially inhibited. The process of endocytosis, proposed to play a major role in epiboly of the yolk syncytial layer (Betchaku, T. and Trinkaus, J. P. (1986) Am. Zool. 26, 193–199), was still observed in nocodazole-treated embryos. Treatment of embryos with taxol led to a delay in all epibolic movements. We propose that the yolk cell microtubules contribute either directly or indirectly to all epibolic movements. However, the epibolic movements of the yolk syncytial layer nuclei and of the blastoderm are not coupled, and only movements of the yolk syncytial nuclei are absolutely dependent on microtubules. We hypothesize that the microtubule network of the syncytial layer and the animal-vegetal set of the yolk cytoplasmic layer contribute differently to various aspects of epiboly. Models that address the mechanisms by which the two microtubule arrays might function during epiboly are discussed.

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Stereological Analyses of Hepatocyte Ultrastructure Monitor Arsenic Liver Burdens

1980 ◽  
Vol 38 ◽  
pp. 442-443
Author(s):  
E. M. B. Sorensen ◽  
R. R. Mitchell ◽  
L. L. Graham
Keyword(s):  
Drainage System ◽  
Water Levels ◽  
Ultrastructural Changes ◽  
Hepatocyte Ultrastructure ◽  
Lepomis Cyanellus ◽  
Large Numbers ◽  
Activation Data ◽  
Water Analyses ◽  
Municipal Lake ◽  
Green Sunfish

Endemic freshwater teleosts were collected from a portion of the Navosota River drainage system which had been inadvertently contaminated with arsenic wastes from a firm manufacturing arsenical pesticides and herbicides. At the time of collection these fish were exposed to a concentration of 13.6 ppm arsenic in the water; levels ranged from 1.0 to 20.0 ppm during the four-month period prior. Scale annuli counts and prior water analyses indicated that these fish had been exposed for a lifetime. Neutron activation data showed that Lepomis cyanellus (green sunfish) had accumulated from 6.1 to 64.2 ppm arsenic in the liver, which is the major detoxification organ in arsenic poisoning. Examination of livers for ultrastructural changes revealed the presence of electron dense bodies and large numbers of autophagic vacuoles (AV) and necrotic bodies (NB) (1), as previously observed in this same species following laboratory exposures to sodium arsenate (2). In addition, abnormal lysosomes (AL), necrotic areas (NA), proliferated rough endoplasmic reticulum (RER), and fibrous bodies (FB) were observed. In order to assess whether the extent of these cellular changes was related to the concentration of arsenic in the liver, stereological measurements of the volume and surface densities of changes were compared with levels of arsenic in the livers of fish from both Municipal Lake and an area known to contain no detectable level of arsenic.

Local interaction rules and collective motion in black neon tetra (Hyphessobrycon herbertaxelrodi) and zebrafish (Danio rerio).

2019 ◽  
Vol 133 (2) ◽  
pp. 143-155 ◽  
Author(s):  
Vicenç Quera ◽  
Elisabet Gimeno ◽  
Francesc S. Beltran ◽  
Ruth Dolado
Keyword(s):  
Danio Rerio ◽  
Collective Motion ◽  
Local Interaction

Developmental Changes in Anxious Children's Cognitions: Implications for research and clinical practice

2013 ◽  
Author(s):  
Melissa E. Tamas ◽  
Robert D. Friedberg ◽  
Rosa M. Poggesi ◽  
Micaela Thordarson ◽  
Lisa C. Hoyman ◽  
...  
Keyword(s):  
Clinical Practice ◽  
Developmental Changes
Sign in / Sign up

Export Citation Format

Share Document