![]() Fertilized egg and mesolecithal Identify the name of the developmental stage depicted. Unfertilized and is an isolecithal egg Label the following structure on the sea star embryo: Blastopore, blastocoel, and archenteron Identify/categorize the type of egg based on its distribution of yolk AND label the following regions: vegetal pole and animal pole. Identify/categorize the type of egg based on its distribution of yolk. Rather, they grow down over the larger yolk cells to envelop them with the progression of growth. A slight depression forms on the surface of the blastula which enlarges to form the archenteron within the gastrula. How does the process of gastrulation differ in sea stars and frogs? 1.)During gastrulation in sea star embryos, the cells at the surface migrate inward towards the blastocoel.Ģ.)During gastrulation in frogs, the cells aline at the surface forming a crescent shaped line along the surface of the blastula. Instead, it is offset toward the animal pole of the embryo due to the presence of large yolk cells of the vegetal pole. An invagination appears at one end of the embryo and cells organize to form the body geometry of the organism.Ģ.) The blastula of frogs is not centrally located. This causes unequal division with cells at the animal pole dividing at a faster rate than the cells at the vegetal pole How does the formation of the blastocoel differ in sea stars and frogs? 1.)Sea stars during formation of blastula, have cells migrate towards the periphery of the embryonic sphere to create a hollow cavity within the spheroid of cells. How does the pattern of cleavage differ in sea stars and frogs? 1.)Sea stars and frogs cleavage differ because sea stars cleavage separates their cells into roughly equal-sized, but distinct, cells.Ģ.)Whereas frogs on the other hand have a third cleavage which occurs slightly above the equator. When cleavage plane occurs perpendicular or parallel to each other, cleavage is characterized as _? Radial cleavage When cleavage planes are restricted to a dome of cytoplasm at one end of the cell, cleavage is characterized as _? Discoidal cleavage What is spiral cleavage? When cleavage planes occur at oblique angles What is superficial cleavage? Due to the unique distribution of yolk in centrolecithal eggs, cleavage occurs only in the cell's periphery Which is larger, a sea star zygote or a frog zygote? A frog zygote is bigger Sea star Early Embryonic Development: Sea star early stages of gastrulation development: Sea star later stage of gastrulation development: Vegetal poles are what? They appear lighter in coloration, and is segregated towards one pole of the egg Animal poles are what? They are the darker pole, and represents the portion of the egg where the embryo will develop. What is fast block in fertilization? When the electrical potential of the egg's plasma membrane changes polarity to block any other sperm from penetrating. What type of cleavage pattern do Centrolecithal eggs undergo? Superficial What organisms are mostly formed from Centrolecithal eggs? Most arthropods What three major processes govern the basic developmental sequence of animals? 1.)Cell divisionģ.)Cell differentiation What does cell division do? It creates new cells through mitosis What does cell migration do? It causes groups of cells to organize and move, to create an animal's body shape What does cell differentiation do? It causes cells to develop different morphological features for specialization toward specific tasks What is polyspermy? Is the entrance of more than one sperm cell What is a fertilization cone? When the sperm comes in contact with the egg, the egg will erect a fertilization cone, which draws the head of the sperm into the egg's plasma membrane. What is meroblastic cleavage? Incomplete cleavage- because of the large, heavily concentrated yolk, cleavage is only partial ,stopping at the border between the embryo and the yolk, and the daughter cells remain connected to each other What organisms are formed from Telolecithal eggs? Birds and reptiles What is Centrolecithal eggs? They also have a large amount of yolk, but the embryo forms a thin layer around the outside of the large, central yolk mass.
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