Câu 7: COMPARE THE FORMATION OF A BLASTULA AND GASTRULATION IN A SEA URCHIN, A FROG, AND A CHICK

Slide1: Here are some basic differences of blastula and gastrula
-Blastula can be described as a hollow sphere of cells, formed by morula and start form the second stage in the process of embryogenesis
-Gastrula is an early multicellular embryo made up of three germinal layers, formed by blastula and star from the third stage in the process of embryogenesis
Slide 2: As you can see from the picture on the left, The Blastula formation of sea urchin is a process by which cells multiply - zygote cells - and form a hollow sphere surrounding a central cavity, or blastocoel.

Gastrula formation in sea urchin is the process by which cells blastula consists of a single layer including about 1000 cells.

Slide 3: The Blastula formation of frog is the process of cell division zygote until a hollow ball of cells appear, which is called blastula . The cavity inside the blastula is called blastocoel.

Gastrulation takes place after cleavage which is a process that gives origin to an organism's interior structure. The blastula folds up on itself during gastrulation to generate three germ layers: ectoderm, mesoderm, and endoderm.

Slide 4: The Blastula formation of chick have a stage of cell division similar of a frog, but at the end of the stage the embryo of polylecithal egg reaches the morula stage, which consists of a disc-shaped mass of cells, several strata in thickness called the blastodisc lying applied to the yolk.

Similar to frogs, in chick, Gastrulation is the process by which cells in the blastula reorganize themselves spatially to generate three layers of cells..
Cau 8: LIST AND EXPLAIN THE FUNCTION OF THE EXTRAEMBRYONIC MEMBRANES

SLIDE 1: Name.
Dring embryonic development the embryo forms for extra embryonic membranes that are ultimately discharged following birth. These membranes include the chorion, the amnion, the yolk sac (Also called umbilical sac), and the allantois.

SLIDE 2: There functions

the chorion Its function includes protecting the embryo from damage by absorbing some of the shock and eventually helping form the chorionic villi which are part of the placenta.

The amnion is the membranous sac that contains a fluid-filled ( phờ lu ịt - phill) cavity that also absorbs shock but also keeps the embryo from drying out and allows some degree of movement. The amnion consist of the ectoderm and mesoderm germ layers.

The allantois and the umbilical vesicle eventually become part of the umbilical cord. In humans, the allantois is used to form some of the blood vessels within the cord while the yolk sac is used to produce some of the red blood cells during early embryological development. In other animals such as birds and reptiles, the yolk sac contains a nutritious (n(y)o͞oˈtriSHəs ) substance called the yolk which is used to nourish the developing embryo.