منابع مشابه
High density cell water in amphibian eggs?
The exchange of isotopic water, 2H2O and H2(18)O has been studied in amphibian eggs. The experiments were carried out with ovarian and body cavity eggs of Rana temporaria and unfertilized eggs of Ambystoma mexicanum. The cytoplasmic diffusion coefficient for H2(18)O was found to be 4.6 x 10(-6) cm2/s, somewhat higher than that for 2H2O, 3.4 x 10(-6) cm2/s. The total change in reduced weight, de...
متن کاملReversal of developmental competence in inverted amphibian eggs.
Inverted amphibian embryos were employed for an analysis of pattern formation in early embryogenesis. Axolotl (Ambystoma) and Xenopus eggs were inverted prior to the first cleavage division and permitted to develop upside down to the early gastrulation stage. In both cases the cleavage patterns of the animal and vegetal hemispheres were reversed. By gastrulation, however, developmental arrest b...
متن کاملThe Mechanism of Cleavage in Amphibian and Sturgeon Eggs.
T H E CLEAVAGE plane in animal cells and eggs is known to be determined by the position of the mitotic apparatus (cf. Wilson, 1925). A displacement of the mitotic apparatus by centrifugation (Harvey, 1935), mechanical deformation of eggs (Rappaport, 1960, 1961) or by microsurgical operation (Carlson, 1952; Waddington, 1952; Kawamura, 1960; Chambers & Chambers, 1961; Dan & Kuno Kojima, 1963) res...
متن کاملThe Osmotic Properties of Living Cells (eggs of Arbacia Punctulata)
WE HAVE ATTEMPTED TO ANSWER THE QUESTION: How nearly ideal, as an osmometer, is the unfertilized Arbacia egg? The following conclusion have been reached: 1. Volumes can be measured accurately over a wide range of pressures since the cell is in general spherical and does not suffer deformation from its own weight or other factors. 2. The product of volume and pressure is approximately constant, ...
متن کاملWindowing chicken eggs for developmental studies.
The study of development has been greatly aided by the use of the chick embryo as an experimental model. The ease of accessibility of the embryo has allowed for experiments to map cell fates using several approaches, including chick quail chimeras and focal dye labeling. In addition, it allows for molecular perturbations of several types, including placement of protein-coated beads and introduc...
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ژورنال
عنوان ژورنال: The Biological Bulletin
سال: 1961
ISSN: 0006-3185,1939-8697
DOI: 10.2307/1539449