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Pinacoderm
The pinacoderm is the outermost layer of body cells (pinacocytes) of organisms of the phylum Porifera (sponges), equivalent to the Epidermis (skin), epidermis in other animals. Structure The pinacoderm is composed of pinacocytes, flattened epithelial cells that can expand or contract to slightly alter the size and shape of the sponge. It also contains porocytes, oval-shaped cells extending from the pinacoderm to the choanoderm (the body layer containing choanocytes). References Sponge anatomy {{animal-anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porifera
Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a Basal (phylogenetics) , basal clade and a sister taxon of the Eumetazoa , diploblasts. They are sessility (motility) , sessile filter feeders that are bound to the seabed, and are one of the most ancient members of macrobenthos, with many historical species being important sponge reef , reef-building organisms. Sponges are multicellular organisms consisting of jelly-like mesohyl sandwiched between two thin layers of cell (biology) , cells, and usually have tube-like bodies full of pores and channels that allow water to circulate through them. They have unspecialized cells that can cellular differentiation , transform into other types and that often migrate between the main cell layers and the mesohyl in the process. They do not have complex nervous system , nervous, digestive system , digestive or circulatory systems. Instead, most rely on maintaining a constant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porocytes
Porocytes are tubular cells which make up the pores of a sponge known as ostia. Description Covering the sponge is a layer of cells known as the pinacoderm, which is composed of pinacocytes. In a sponge, pinacocytes are a thin, elastic layer which keeps water out. Between the pinacocytes, there are the porocytes that allow water into the sponge. Myocyte A muscle cell, also known as a myocyte, is a mature contractile Cell (biology), cell in the muscle of an animal. In humans and other vertebrates there are three types: skeletal muscle, skeletal, smooth muscle, smooth, and Cardiac muscle, cardiac ...s are small muscular cells that open and close the porocytes. They also form a circular ring around the osculum and help in closing and opening of it. Once through the pores, water travels down canals. The opening to a porocyte is a pore known as an ostium. In sponges, like Scypha, there are some cells that have an intracellular pore. These cells are known as porocytes. They are pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choanoderm
The choanoderm is a type of cell layer composed of flagellated collar cells, or choanocytes, found in sponges. The sponge body is mostly a connective tissue; the mesohyl, over which are applied epithelioid monolayers of cells, the outer pinacoderm and the inner choanoderm. Importance Most aspects of sponge biology, including feeding, reproduction, and gas exchange, depend on a low pressure flow of water generated by the flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ... of the choanoderm. Three grades of organization, asconoid, syconoid, and leuconoid, reflect the degree of elaboration of the choanoderm layer and mesohyl. In the asconoid plan the interior water space, or atrium, is large and unpartitioned. In the syconoid plan the periphery of the atrium is divided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epidermis (skin)
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the amount of water released from the body into the atmosphere through transepidermal water loss. The epidermis is composed of multiple layers of flattened cells that overlie a base layer ( stratum basale) composed of columnar cells arranged perpendicularly. The layers of cells develop from stem cells in the basal layer. The thickness of the epidermis varies from 31.2μm for the penis to 596.6μm for the sole of the foot with most being roughly 90μm. Thickness does not vary between the sexes but becomes thinner with age. The human epidermis is an example of epithelium, particularly a stratified squamous epithelium. The word epidermis is derived through Latin , itself and . Something related to or part of the epidermis is termed epidermal. Structure ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pinacocyte
Pinacocytes are flat cells found on the outside of sponges, as well as the internal canals of a sponge. Pinacocytes are not specific to the sponge however. It was discovered that pinacocytes do not have as many sponge specific genes. These genes suggest that pinacocytes had evolved before the metazoan time period, which is, before porifera had evolved. Function Pinacocytes are part of the epithelium Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ... in sponges. They play a role in movement (contracting and stretching), cell adhesion, signaling, phagocytosis, and polarity. Pinacocytes are filled with mesohyl which is a gel like substance that helps maintain the shape and structure of the sponge. Types Basipinacocytes These are the cells in contact with the sponge's substrate (the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choanocytes
Choanocytes (also known as "collar cells") are cells that line the interior of asconoid, syconoid and leuconoid body types of sponges that contain a central flagellum, or ''cilium,'' surrounded by a collar of microvilli which are connected by a thin membrane. They make up the choanoderm, a type of cell layer found in sponges. The cell has the closest resemblance to the choanoflagellates which are the closest related single celled protists to the animal kingdom (metazoans). The flagellae beat regularly, creating a water flow across the microvilli which can then filter nutrients from the water taken from the collar of the sponge. Food particles are then phagocytosed by the cell.Anderson, D. (2001) ''Invertebrate Zoology'' Oxford University Press Choanocytes are found dotting the surface of the spongocoel in asconoid sponges and the radial canals in syconoid sponges, but they comprise entirely the chambers in leuconoid sponges. Morphology Function By cooperatively mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
