After the zygote begins to divide, a fluid-filled ball of cells, called blastocyst attaches to the uterine wall.
<span>It is the stage of implantation during the prenatal development. The blastocyst consists of an inner cell mass and the outer layer -the trophoblast. Trophoblast surrounds the inner cell mass and a fluid-filled cavity - blastocoele. Inner cell mass will form embryo and trophoblast gives rise to the placenta.</span>
* More than 40 proteins and glycoproteins involved in the complement system are synthesized by the liver, macrophages, epithelial cells, they are present in the blood in plasmatic form, membrane, some have an enzymatic activity, regulator or membrane receptorThese are elements of the humoral innate immune response, they fight infections, purify immune complexes and apoptotic bodies.
<span>There are indeed three ways to activate the complement:</span>
Classical pathway: Activated by Immunoglobulins in immune complexes, aggregated Immunoglobulins, DNA, CRP, apoptotic bodies .......it involves nine fractions, starting with C1, then C4, C2, C3, to form a classical C5 convertase, then, activation of C5, C6, C7, C8, C9.
Alternative pathway: activated by polysaccharides (bacterial endotoxin), vascular wall poor in sialic acid, aggregated IgE ...C3b like is the first component in the alternate channel cascade, it will create an amplification loop, and form an alternative C5 convertase.
Lecithin pathway: Activated by mannose, fucose (carbohydrate of microorganisms)The first component is the complex MBL / MASP1 / MASP2: "mannose-binding protein": works according to the same principle as the complex C1 of the classical way (MASP2 cleaves the C4 and the rest of the cascade is equivalent to that of the classical way).
the three ways have the same outcome: A C5 convertase (formed by one of the pathways) cleaves C5 into C5a and C5b: C5b is deposited far from other fractions on the antigenic surface. The fixation of C5b in the cell is followed by that of C6, C7, C8, and C9 (9 molecules of C9): formation of the membrane attack complex (MAC) ==> Death of the cell by osmotic shock
The role of deep-sea coral reefs in the environment is to provide critical habitat for many other organisms. So, the correct option is C.
<h3>What do you understand about Coral reefs?</h3>
A coral reef is an underwater ecosystem characterized by reef-building corals.
Coral reefs provide critical habitat for many invertebrates and fishes. These organisms are also known as cold-water corals, as they are found in the deeper and darker part of the ocean where the temperature is extremely low.
Therefore, the role of deep-sea coral reefs in the environment is to provide critical habitat for many other organisms.
To learn more about the Coral reefs, refer to the link:
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