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The egg cell or ovum (pl.: ova) is the female reproductive cell, or gamete, [1] in most anisogamous organisms (organisms that reproduce sexually with a larger, female gamete and a smaller, male one). The term is used when the female gamete is not capable of movement (non- motile ).
Egg activation is stimulated by mechanical deformation associated with traversing through the narrow channel in the oviduct and requires the presence of Ca2+. [3] During egg activation, the vitelline membrane proteins are crosslinked via disulfide remodeling; the structure rigidifies and becomes impermeable to water but remains gas permeable. [ 4 ]
The innermost membrane of all animal eggs except some cnidarians is called the vitelline membrane. Some invertebrates and some lower chordate eggs are covered by this membrane only, while most have other membranes. [10] Frog and bird eggs have a very thin vitelline membrane which are surrounded by either a jelly layer (frogs) or other membranes ...
Eggshell membrane is the clear film lining the chicken eggshell displayed. Eggshell membrane or shell membrane is the clear film lining eggshells, visible when one peels a boiled bird egg. Chicken eggshell membranes are used as a dietary supplement. Eggshell membrane is derived commercially from the eggshells of industrial processors.
Mesolecithal eggs have comparatively more yolk than the microlecithal eggs. The yolk is concentrated in one part of the egg (the vegetal pole), with the cell nucleus and most of the cytoplasm in the other (the animal pole). The cell cleavage is uneven, and mainly concentrated in the cytoplasma-rich animal pole. [3]
[citation needed] When unseparated, the calcium carbonate eggshell and protein-rich membrane are useless. [17] Recent inventions have allowed for the egg cracking industry to separate the eggshell from the eggshell membrane. The eggshell is mostly made up of calcium carbonate and the membrane is valuable protein.
The zona pellucida is an extracellular matrix that surrounds the plasma membrane of the egg cell. It helps protect the egg, and has an essential role in fertilization by sperm. It is surrounded by the corona radiata. The corona is composed of cells that care for the egg when it is emitted from the ovary. [1]
The cell wall acts to protect the cell mechanically and chemically from its environment, and is an additional layer of protection to the cell membrane. Different types of cell have cell walls made up of different materials; plant cell walls are primarily made up of cellulose, fungi cell walls are made up of chitin and bacteria cell walls are ...