Gastrulation in frog and chick. Comparison of Amphibian and Bird Embryos essays 2022-10-22
Gastrulation in frog and chick Rating:
Gastrulation is a crucial stage in the development of all multicellular organisms, during which the embryonic cells rearrange and differentiate to form the three primary germ layers that will eventually give rise to all the body's organs and tissues. In this essay, we will explore the process of gastrulation in two model organisms: the frog and the chick.
In frogs, gastrulation begins around the third day of development, when the fertilized egg undergoes cleavage to form a hollow ball of cells called the blastula. During the next stage, known as blastulation, the blastula invaginates at one end to form a cup-like structure called the blastopore. This process is driven by the migration of cells known as involuting mesoderm, which move inward towards the center of the blastula.
As the involuting mesoderm cells reach the center of the blastula, they begin to differentiate into the three primary germ layers: the ectoderm, mesoderm, and endoderm. The ectoderm will give rise to the skin, nervous system, and sensory organs, while the mesoderm will form the muscles, bones, and circulatory system. The endoderm, meanwhile, will eventually become the lining of the gut and respiratory and urinary tracts.
In the chick, gastrulation begins slightly later, around the fourth day of development, and involves a process called epiboly. During epiboly, cells at the edge of the blastula begin to migrate over the top of the cells in the center, eventually enclosing them to form the primitive streak. The cells at the leading edge of the primitive streak then begin to differentiate into the three primary germ layers, in a process similar to that seen in frogs.
One key difference between the two processes is the way in which the germ layers are formed. In frogs, the involuting mesoderm cells move inward towards the center of the blastula, while in chicks, the germ layers are formed by cells at the edge of the blastula migrating over the top of the cells in the center. Despite this difference, the end result is the same: the formation of the three primary germ layers that will give rise to all the body's organs and tissues.
Overall, gastrulation is a complex and dynamic process that plays a crucial role in the development of all multicellular organisms. By studying the process in model organisms such as frogs and chicks, we can gain a better understanding of how the body's organs and tissues are formed and how development can go awry.
Gastrulation in Frogs
Finally the node regresses to its most posterior position, eventually forming the anal region in true deuterostome fashion. The cells entering the inside of the avian embryo form a lossely connected mesenchyme. The outer layer of the yolk sac starts to form new cells to the outside. ADVERTISEMENTS: 2 The primitive node corresponds to the dorsal lip of blastopore future tail bud. After this process is finished, a blastopore is formed, and the yolk is tucked inside. This shift is an active process, an act of movement by the cells concerned.
The notochord of the frog comes from the cells in the dorsal lip of the blastopore and takes it's place in the roof of the archenteron. Reproduction in most animals involves fertilization: a process where the male and the female gametes fuse to form a fertilized egg called a zygote. Positioning the blastopore The vegetal cells are crucial in identifying the place of the blastopore, as is the point of sperm entry. A primitive streak is formed by the cells of the upper layer of cells called epiblast, which normally move to the midline of the developing embryo. As the days and hours progress, the zygote starts multiplying its cells until eventually it is a bundle of many cells. During the period of cleavage the three regions become subdivided into blastomeres without the cytoplasmic substances having been displaced to any great extent.
The rim of the blastopore, however, continues to contract and at last covers the yolk plug altogether. The mesodermal layer is thickest in the roof of the archenteron, where the mesoderm adjoins the notochord; it is thinned out in the lateral part and still more so in the ventral part of the embryo. The endoderm also slightly pokes out of the gastrula in the form of a yolk plug. The middle layer is the mesoderm. The endoderm in frogs lines the archenteron and the ectoderm is formed from cells on the outside of the gastrula, along with newly formed cells.
The concentration toward the dorsal side of the embryo, noted in respect to the notochordal and nervous system material, is also very distinct in the case of the mesodermal mantle. Blastocoel is displaced to the opposite side of the dorsal blastopore lip by new cells entering the embryo. This disc is called blastodisc. Also, the movement of the superficial material can be seen to be most rapid and extensive on the dorsal meridian of the embryo. This narrow part of the archenteron later becomes the mid-gut of the embryo.
What are the similarities and differences of gastrulation in the development of starfish, frog, and chick?
As the streak regresses posteriorly, the embryo develops anterior to it. Further, the cellular movement of these cells is correlated with the presence of a fibronectin meshwork in the extra cellular basal lamina of the epiblast cells. Initially, the cells in the blastula are normally together. What is the Difference Between Frog and Chick Gastrulation? Cells begin moving towards the middle of the embryo and form the primitive streak and Henson's node. The layer of endoderm in the floor of the archenteron is very thick, and the cavity of the archenteron is therefore reduced posteriorly to a rather narrow canal underneath the chordomesodermal mantle. This situation is again similar to amphibians.
Shortly before hatching the shrivelled up remains of the yolk sac is retracted into the abdominal cavity of the embryo, and the walls of the abdominal cavity close behind it. The marginal blastomeres are continuous with the uncleaved cytoplasm at their outer edges. It may be noticed then that on the dorsal side of the embryo the floor of the blastocoele becomes raised, and a broad tongue-like mass of cells is seen rising against the inner surface of the blastoderm. Generally, a human embryo has two flat layers of cells during the second week after fertilization. These deep-moving cells give rise to all the endodermal organs of the embryo as well as to most of the extra embryonic membranes.
It is lined by mesoderm of somatopleure and splanchnopleure. Overview of Gastrulation Gastrulation is a phase in the embryonic development of animals where the blastula reorganizes itself into a gastrula. The inward migrating cells also spread out sideways and forward from the anterior end of primitive streak. As the mesoderm moves from the posterior end of the embryo represented by the blastopore toward the anterior end, there remains at the anterior end a region which the mesodermal mantle has not yet reached. The cells containing the basophilic cytoplasm are clearly discernible even as to shape. In the Anura, the mesoderm does not split off from the adjoining endoderm until gastrulation is nearly finished. The animal region is the part of the blastoderm that does not pass into the interior by way of the blastopore.
Gastrulation in Chick: Its Significance and Mechanism (1252 Word)
Figure 02: The Development of the Chick Cell invagination occurs thought this blastopore. The amnion protects the embryo from desiccation and sudden temperature changes. These foetal membranes are amnion, chorion or serosa, allantois and yolk sac. This layer will become many different linings but most superficially will become the outer layer of the skin, part of the esophagus, as well as many other organs and nerve tissue. Meanwhile, cells continue migrating inward through the primitive streak. It is in a cylindrical form which is much longer on the dorsal than the ventral side. Formation of Coelom : After the somites and the lateral plates have been formed, the mesoderm of lateral plate splits into two layers- the external or parietal layer and the internal or visceral layer.