Definitive Yolk sac
A blastocoel is the fluid-filled cavity in the blastula.
blastocoel
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The central cavity within the blastula is called the blastocoel. It is filled with fluid and is surrounded by a layer of cells called the blastoderm.
A blastocoele is the fluid-filled cavity in the blastula.
The digestive tract develops from a central cavity called the blastocoel. During embryonic development, the blastocoel is surrounded by the endoderm, which eventually forms the lining of the digestive system. This process is known as gastrulation.
The blastocoel of the frog blastula is called eccentric because it is located closer to one pole of the blastula instead of being centrally located. This eccentric positioning is due to the unequal distribution of yolk in the frog egg, causing the blastocoel to be displaced towards the animal pole where there is less yolk.
The blastocoel has two main functions. 1.It permits cell migration during gastrulation. 2.It prevents the animal cells, destined to become ectoderm, from premature induction by the underlying vegetal cells into mesoderm.
The blastula is a single-layered ball with a fluid-filled cavity called the BLASTOCOEL in the middle (which the morula stage lacks). --Side note: The morula is a ball of cells about the same size as the original zygote and the large number of embryonic cells of the morula arrange themselves into a blastula, with the blastocoel in the middle.
C. hemocoel
The frog blastula is formed through holoblastic cleavage, resulting in a multicellular blastula with a fluid-filled cavity (blastocoel). In contrast, the sea star blastula is formed through radial holoblastic cleavage, leading to a solid blastula with no blastocoel. Additionally, the frog blastula undergoes gastrulation to form a gastrula with three germ layers, while the sea star blastula directly develops into a bipinnaria larva without gastrulation.
A blastula typically consists of a single layer of cells called the blastoderm. This layer forms during early embryonic development and surrounds a fluid-filled cavity called the blastocoel.