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The vitelline membrane of the hen is made of two main protein layers that provide support for the yolk and separation from the albumen.The inner layer is known as the perivitelline lamina. [1]
This can be a complex structure, and it may have different layers, including an outermost layer called an exochorion. Eggs which must survive in dry conditions usually have hard eggshells, made mostly of dehydrated or mineralized proteins with pore systems to allow respiration. Arthropod eggs can have extensive ornamentation on their outer ...
The major role of the vitelline membrane is to prevent the mixing of the yolk and albumen and also act as an important anti-microbial barrier, as indicated by the high content of lysozyme in the outer layer [1] Vitelline membrane outer layer protein I (VMO-I) binds tightly to ovomucin fibrils, which construct the backbone of the outer layer membrane.
The vitelline membrane consists of two major layers found below the ovary and the outer layer found in the oviduct. This membrane supports the yolk and separates from the albumen , or egg white. The proteins that primarily compose the vitelline membrane are the lysozyme and ovomucin foundational for membrane growth during embryonic development.
The chorioallantoic membrane is composed of three layers. The first is the chorionic epithelium that is the external layer present immediately below the shell membrane. [ 2 ] It consist of epithelial cells that arise from chorionic ectoderm .
The zona pellucida is a translucent matrix of cross-linked glycoprotein filaments that surrounds the mammalian oocyte and is 6.5–20 μm thick depending on the species. Its formation, which depends on a conserved zona pellucida-like (ZP) module that mediates the polymerization of egg coat components, [2] is critical to successful fertilization. [3]
This core is surrounded by two layers of trophoblasts, the cytotrophoblast and the syncytiotrophoblast. The cytotrophoblast is a layer of mono-nucleated cells that resides underneath the syncytiotrophoblast. [6] The syncytiotrophoblast is composed of fused cytotrophoblasts which then form a layer that covers the placental surface. [6]
The yolk makes up about 33% of the liquid weight of the egg; it contains about 60 kilocalories (250 kJ), three times the energy content of the egg white, mostly due to its fat content. [clarification needed] All of the fat-soluble vitamins (A, D, E and K) are found in the egg yolk. Egg yolk is one of the few foods naturally containing vitamin D.