Mesoderm

A coelomate has a fluid filled body cavity, which is completely lined by the mesoderm. The organs of a coelomate are suspended within the fluid filled body cavity. This provides protection from any shock put on the organs. This fluid also provides shape to animals without a hard skeleton. Animals like Arthropoda and Echinodermata are examples of coelomates. Acoelomates lack internal cavities and fluid altogether. Their organs are located within the mesoderm which means less protected from shock or pressure. Aceolomates could also have a spongocoel which is the central cavity in a Porifera, a diploblastic organization with mesoglea like a Cnidaria, or a solid layer of mesoderm like a Platyhelminthes. Protostome development means that an organism develops a mouth first from the blastopore and anus second. In the early stage of development, the embryos undergo spiral cleavage, which mean micromeres between micromeres. The cells that formed are determinate, which means that the blastomere fate is established during the early stages of development. Animals like Platyhelminthes, Molluscs, and Arthropods are examples of some protostomes. Deuterostome development means that an organism develops anus first near the blastopore…

Many roundworm species are free-living. They have a body cavity that is between the endoderm and mesoderm tissues. The endoderm germ layer is like an internal layer and the mesoderm germ layer is like a middle layer. The body cavity is known as a pseudocoelom, due to it only being relatively lined with the mesoderm tissue. Roundworms have a digestive tract that consists of two openings, which are a mouth and an anus. Roundworms need to depend on diffusion, or the natural spreading of particles…

invertebrates (Myers, 2002). Typically, they can be found in marine water, freshwater, and general damp terrestrial habitats, being free living, but more than often parasitic (Myers, 2002). Additionally, platyhelminths are known to have three germ layers: an endoderm, ectoderm, and a mesoderm. The addition of the mesoderm allows animals to form true organ systems; however, this is all truly possible due to the mesoderm’s key feature, the coelom- a fluid-filled cavity that stores and protects…

Animals in the phylum Platyhelminthes, widely known as flatworms, were the first to develop bilateral symmetry, triploblasty, and cephalization. Bilateral symmetry means that an animal's left and right side of their body are mirror images of each other. Cephalization is the development of nervous tissues becoming concentrated towards the anterior end of an animal. Triploblasty means that an organism has three tissue layers, an ectoderm (outer layer), mesoderm (middle layer), and an endoderm…

or pluripotency (Image from: Mitalipov & Wolf, 2009). Totipotency, depicted by its name as total power is the ability to produce and differentiate into any type of cells found in the organism (Figure 1). This type of stem cell has the ability to recreate the whole organism. When an egg is fertilized by a sperm, it creates a totipotent cell (also known as a zygote) (Asch, Simerly, Ord, Ord, & Schatten, 1995). The totipotent cell will develop to different layers of the organism (endoderm,…

During this lab observations of the external and internal structures of seastars were examined through dissection. Most notably, seastars are creatures that are deuterostomes. First of all, deuterostomes are organisms within Echinodermata and Chordate phylum that developed anus first. The egg for echinoderms have a little quantity of yolk that allows the egg to divide in its first and second cleavage stage into four equal blastomeres; this is also known as holoblastic cleavage. Although, if the…

The three layers (germ layers) are called ectoderm, mesoderm, and endoderm. (Biology.OpenStax.1755). The final stage is organogenesis (important stage) when the three germ layers of the gastrula develop various body organs (Biology.OpenStax.1756). During this stage, the brain, skin, and nervous system arises from the ectoderm, while the blood cells, heart, and muscle cells rise to the mesoderm. The digestive system, liver, and other internal organs give rise to the endoderm…

Eighteen somites (pairs), somites are divisions of an animal’s body containing the same internal structures. They are made up of paraxial mesoderm, paraxial mesoderm is the area of the mesoderm in the neurulating embryo which is produced with the neural tube. Somites later subdivide into sclerotomes, myotomes and dermatomes. [9] In figure 2 the otic vesicles can be seen, one is visible, the other is denoted only by a slight protuberance. The neural tube can also be seen, this has developed from…

blastocyst the embryoblast forms two layers of cells, known as the hypoblast and epiblast. By the end of the pre-embryonic period cavities have formed and the connecting stalk, which will eventually become the umbilical cord, is also present. The embryonic period begins and it is characterized as the time the embryo is most susceptible to tetragons. This period lasts from the third to eighth week of development and begins with the crucial process of gastrulation. Gastrulation will establish…

addition, in many tissues serve as an internal repair system, stem cells divide nonstop in order to replenish other cells throughout the persons’ lifetime. When a stem cell divides, each new cell may either remain a stem cell or become another type of cell with a more specialized function, thus they are a tremendously serious matter, not just in the USA, but all around the world. There are two different types of stem cells: embryonic and adult. Embryonic stem cells are undifferentiated cells…