Studies on Amphibian Yolk

Karasaki, Shuichi

doi:10.1083/jcb.18.1.135

Cited by 135 publications

(16 citation statements)

References 36 publications

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“…The crystalline arrangement of the lipovitellin-phosvitin subunits in the platelet has been investigated with X-ray diffraction (12,13), and electron microscopy of sectioned platelets (1,16,27,35,36). The X-ray studies provided structural data on the unit cell of the X-ray scattering elements within the platelets, and the predicted subunit spacings are in fair agreement with results of the electron microscopic studies.…”

supporting

confidence: 63%

Amphibian yolk platelet ultrastructure visualized by freeze-etching

Leonard

Deamer

Armstrong

1972

Journal of Ultrastructure Research

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supporting

confidence: 63%

Amphibian yolk platelet ultrastructure visualized by freeze-etching

Leonard

Deamer

Armstrong

1972

Journal of Ultrastructure Research

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“…are aggregated in crystalline formations in blastomeres of the blastula, but we have not observed an internal crystalline structure in membranebounded granules like that found in the yolk platelets of amphibians (18).…”

Section: Thomas L Lentz and J P Trinkaus Cytodifferentiation Of Fumentioning

confidence: 80%

“…8). Although the composition of these structures is unknown, they closely resemble the crystalline structure of amphibian yolk platelets (18) The surfaces of both the enveloping layer and deep blastomeres are usually smooth without pinocytotic vesicles (Fig. 10).…”

Section: Blastulamentioning

confidence: 99%

A FINE STRUCTURAL STUDY OF CYTODIFFERENTIATION DURING CLEAVAGE, BLASTULA, AND GASTRULA STAGES OF FUNDULUS HETEROCLITUS

Lentz

Trinkaus

1967

The Journal of Cell Biology

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The fine structure of cleavage, blastula, and gastrula stages of Fundulus heteroclitus was investigated. Cleavage blastomeres arc relatively unspccialized, containing few or poorly developcd organelles. Beginning in blastula stages, signs of differentiation were noted, including development of the cndoplasmic reticulum and Golgi apparatus and appearance of a primary nucleolus and polyribosomcs. More extensive structural specializations occur in gastrula stages, including further development of the endoplasmic reticulum and appearance of a granular component in the nucleolus. These changes are associated with cell differentiation and an increascd capacity for protein synthesis, and may bc preparatory to subsequent histogenesis. The periblast is a continuous syncytial cytoplasmic laycr located between the blastodisc and yolk and is formed during late cleavage by incomplete division of the cytoplasm of the blastodisc. Cytoplasmic projections extend from the periblast (and from the basal region of cleavage blastomercs prior to formation of the periblast) into the yolk and function in uptake of yolk material in the absence of pinocytosis. Yolk material appears to be digested by the periblast and transferred into the segmentation cavity where it is available to the blastomeres. Protein granules, lipid droplets, glycogen, crystalline arrays, and multivesicular bodies are related to food storage and utilization by blastomeres. The yolk gel layer enclosing the yolk sphere was found to be a thin layer of cytoplasm continuous with the margin of the periblast and is renamed the yolk cytoplasmic layer.

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“…In 1957, Wischnitzer was the first to observe with the electron microscope that the central region (main body) of amphibian yolk platelets has a crystalline matrix surrounded by amorphous material [termed a superficial layer by Karasaki (1963a)l and a membrane. Since that time, similar observations have been made for almost all anamniotic taxa, although variations [such as the presence of lipid droplets in the superficial layer (Richter, 198711 have occasionally been found.…”

Section: Vitellogenesismentioning

confidence: 99%

Ultrastructural aspects of oogenesis and oocyte growth in fish and amphibians

Wallace

Selman

1990

J. Elec. Microsc. Tech.

235

152

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Oogenesis, the early events of primary oocyte growth (meiotic arrest, synapsis, ribosomal gene duplication), and folliculogenesis can be seen to particular advantage in the germinal ridge of the syngnathan ovary. After budding off the germinal ridge (a compartment of the luminal epithelium), nascent follicles then enter into a linear array of developing follicles within which temporal and stage-specific events can be correlated with spatial distribution. Prominent features of the later phase of primary oocyte growth include intense transcriptional activity and the formation and subsequent dispersal of the Balbiani vitelline body (mitochondrial cloud) concomitant with an increase in cytoplasmic organelles and volume. Further oocyte growth is characterized by a period of cortical alveolus (in teleosts) or cortical granule (in anurans) formation, in which Golgi elements play a predominant role, and finally vitellogenesis. The latter process, which is responsible for the preponderance of oocyte growth, includes the hepatic synthesis and secretion of vitellogenin (VTG), the uptake of VTG from the bloodstream into the oocyte by receptor-mediated endocytosis, and the transport of VTG via endosomes and multivesicular bodies to forming yolk platelets. In the process, VTG is proteolytically cleaved into the yolk proteins, which assume either a monoclinic (in cyclostomes) or orthorhombic (in teleosts and amphibians) crystalline array. Other structures associated with the growing oocyte are also briefly discussed, including nuage, the vitelline envelope, intercellular junctions between the oocyte and overlying follicle cells, pigment, intramitochondrial crystals in ranidae, and annulate lamellae.

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Studies on Amphibian Yolk

Cited by 135 publications

References 36 publications

Amphibian yolk platelet ultrastructure visualized by freeze-etching

Amphibian yolk platelet ultrastructure visualized by freeze-etching

A FINE STRUCTURAL STUDY OF CYTODIFFERENTIATION DURING CLEAVAGE, BLASTULA, AND GASTRULA STAGES OF FUNDULUS HETEROCLITUS

Ultrastructural aspects of oogenesis and oocyte growth in fish and amphibians

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