Biology Questions
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In addition to invagination and involution, the cells in the outer layer will continue to push down and wrap down. Spread of an outside cell layer to envelop a yolk mass or deeper layer.
In gastrulation, three germ layers (ectoderm, mesoderm, endoderm) are formed. The midline of the mesoderm will mosaic together to form a cylindrical structure called notochord.
Meroblastic cleavage. Eggs of fish and reptiles also belong to this type.
The side away from the nucleus or the side with more yolk.
Discoidal cleavage is when the small part of the cell cannot be completely separated and forms a disc-like structure.
After invagination, the whole layer moves forward to conduct involution. The blastocoel in the archenteron is replaced progressively. The lip is pushed to the posterior position due to epiboly.
After the cells in the dorsal lip invaginate, the cells inside will pull the cells around them and move forward along the inner edge of the whole layer, forming a tube called archenteron.
During cleavage, morula and blastula are formed. The main feature of blastula is it begins to form a cavity in the middle. The cavity is called a blastocoel. Summary: blastula is an embryo with a distinct blastocoel.
the cell looks like a mulberry and is called morula.
The sperm enters the egg, then the outer ring called the fertilization envelop bulges. The bulging of membrane is caused by release of calcium ions.
When cell proliferation comes to a certain amount of cells, the cells begin to migrate. During migration, a structure called an archenteron (gastrocoel) is formed. This stage is called gastrulation. During migration, three germ layers of the embryo are also differentiated: ectoderm, mesoderm, and endoderm.Summary:• migration begins• archenteron (gastrocoel) formation• germ layer formation: ectoderm, mesoderm, andoderm
As cells increase to a certain number during cell proliferation, cells begin to move. One of the cell movements is migration.
Notochord is formed first, then the neurulation occurs to form the neural tube. Somite, neural crest, or organs such as front and hind limbs, heart, eyes, etc., are gradually produced during the process of organogenesis.
The yolk is not evenly distributed, and the top. of the egg has less yolk while the bottom has more yolk. Therefore, when it divides, the side with more yolk will divide more slowly while the side with less yolk will divide faster.
The yolk content affects the cleavage. The yolk inhibits the activity of the cells. Therefore, parts with more yolk will result in lower cell activity.
Cell proliferation makes a zygote from a single cell and turns them into an embryo with multiple cells
Cells begin to differentiate to form various tissues and organs when they migrate to their target location.
The three germ layers: ectoderm, mesoderm, and endoderm, are formed during the process of migration in gastrulation.
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