| The nucleus must be taken from the blastula and gastrula stages of frog embryos. |
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| At blastula stage 8, cells forming the blastocoelic roof were cultured in isolation as explants. |
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| They migrate along the inner face of the blastula wall to form a ring in the vegetal region and lay down calcareous skeletal rods. |
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| A lot of research has gone into answering that, and determining the earliest stage at which the blastula breaks symmetry. |
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| Gastrulation in its broadest sense is the reorganization of the cells of the blastula to form a multilayered embryo, the gastrula. |
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| At this stage, the blastula is in the form of a hollow sphere with radial symmetry. |
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| Note the blastula in reptiles is called a blastoderm or blastodisk because the divisions have been concentrated into a thin disk of cells at the animal pole. |
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| How is it possible that in the past six months, this microscopic blastula has transformed into a being with its own organs, spinal cord and brain? |
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| After the blastula develops, it undergoes transition to the gastrula, a process called gastrulation. |
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| If it will grow to that stage in the form of blastula, then on the inner cell mass are the embryonic stem cells. |
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| Covered with cilia, the sea-urchin blastula swims in the water and proceeds with gastrulation. |
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| The same procedure, of course, is used in cloning an individual, except that before it gets to the blastula stage it is implanted back into the womb and allowed to grow to create an individual. |
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| The first three to four months are spent with the blastula in suspended development before it implants itself in the uterus. |
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| Methylation is complete by blastula stage. |
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| The blastula, which consists of only one cell layer, undergoes a dramatic reshuffling of blastomeres preparatory to the development of the various organ systems of the animal's body. |
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| In most mammals the blastula attaches itself to the uterine lining, thus stimulating the formation of a placenta, which will transfer nutrients from the mother to the growing embryo. |
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| This is possible, because, when they mate in spring, before the pregnancy begins, because the fertilized egg will grow only up to the vesicle or hollow germ stage, the so-called blastula stage. |
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| In a few species, the blastula contains supplies of nutrient yolk and lacks arms, since it has no need to feed. |
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| Important developmental processes observed included cleavage, formation of a blastula, epiboly, gastrulation, neurulation, organogenesis, and hatching. |
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| The pockmarked spherical body and pointy-petaled seedpod in Aurlia Gouthroii Blastula and Aurlia Gouthroii Blastula are decidedly more sinister in ambience. |
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