Heredity and Development Second Edition (1972) / Chapter Skim
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10 A Synopsis of Development of the Amphibian Embryo
10 A Synopsis of Development of the Amphibian Embryo
Pages 229-241
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From page 229... ...
Those seeking to answer embryological questions by experimenting on living embryos previously could work only during the relatively short breeding season. Since the 1930s, however, it has been possible to obtain eggs from some species by injecting them with hormones.
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From page 230... ...
The animal hemisphere, with the animal pole in its center, is the pigmented half of the embryo. The vegetal hemisphere is the unpigmented half of the embryo that has the vegetal pole in its center.
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From page 231... ...
This furrow slowly extends through the embryo until it is divided into two cells. Preceding this external indication of mitosis, the nucleus had gone through the usual prophase, metaphase, anaphase, and telophase stages, and each daughter cells receives a diploid set of chromosomes.
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From page 232... ...
The rate of mitosis of the cells of the animal hemisphere is more rapid than that of the cells of the vegetal hemisphere, so they are more numerous and smaller. If the embryo is turned upside down, the much larger vegetal hemisphere cells are visible (Fig.
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From page 233... ...
Gastrulation is a process of development that leads to a complete reorganization of the embryo. All of the cells of the area corresponding roughly to the vegetal hemisphere move to the interior of the embryo.
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From page 235... ...
At 50 hours, the two neural folds have come together and the neural groove closes off as an internal neural tube (Fig.
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From page 237... ...
A tiny tail is forming. In the lateral and ventral view, the mucus glands are seen as prominent structures.
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From page 239... ...
Tailbud. Ventral view.
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From page 241... ...
Suggested Readings These books give more complete information on normal development of the amphibian embryo. These references apply to Chapter 11 as well.
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