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In zoology, the epidermis is an epithelium (sheet of cells) that covers the body of a eumetazoan (animal more complex than a sponge). [1] [2] Eumetazoa have a cavity lined with a similar epithelium, the gastrodermis, which forms a boundary with the epidermis at the mouth. [2] Sponges have no epithelium, and therefore no epidermis or ...
Some animals, like cnidarians, produce two germ layers (the ectoderm and endoderm) making them diploblastic. Other animals such as bilaterians produce a third layer (the mesoderm) between these two layers, making them triploblastic. Germ layers eventually give rise to all of an animal's tissues and organs through the process of organogenesis.
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. [1] The epidermal layer provides a barrier to infection from environmental pathogens [ 2 ] and regulates the amount of water released from the body into the atmosphere through transepidermal water loss .
The ectoderm is one of the three primary germ layers formed in early embryonic development.It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). [1]
Epidermis In botany, a cortex is an outer layer of a stem or root in a vascular plant , lying below the epidermis but outside of the vascular bundles . [ 1 ] The cortex is composed mostly of large thin-walled parenchyma cells of the ground tissue system and shows little to no structural differentiation. [ 2 ]
The endodermis is the boundary between the cortex and the stele. In many seedless plants, such as ferns, the endodermis is a distinct layer of cells immediately outside the vascular cylinder (stele) in roots and shoots. In most seed plants, especially woody types, the endodermis is present in roots but not in stems.
Roots are specialized for the uptake of water, nutrients (including ions for proper function). [12] Similar to the endodermis, the exodermis contains very compact cells and is surrounded by a Casparian band, two features which are used to restrict the flow of water to a symplastic fashion (through the cytoplasm) rather than apoplastic fashion which (through the cell wall) flow through passages ...
The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm. [1] [2] The mesoderm forms mesenchyme, mesothelium and coelomocytes. Mesothelium lines coeloms.