The body wall ' which encloses the spongocoel , is relatively simple.It consists of two cellular layers,the pinacoderm and choanoderm with a non-cellular mesenchyme in between.
PINACODERM- It consist of thin and flat polygonal cells, the pinacocytes .It help in the protection to the body.The pinacocytes are hexagonal in surface with thin margin and a bulging central part containing a nucleus. The margin contractility so that the sponge can increage or decrease slightly in size.In the body wall are special large and tubular cells called the porocytes. They are supused to be a modified tubular pinacocytes. Each porocyte contains a central like space,communicating with the outside as well as the spongoel. These spaces are called the ostia or dermal pores or incurrent pores. These help water to flow from outside into the spongoel.
CHOANODERM- The choanoderm cells are also called gastrodermis.It consist of a single layer of flagellated cells the choanocytes.The choanocyte consist of an ovoid cell with free end bearing a transparent contractile collar.The collar surrounds a single long flagellum which arises long flagellum from basal granule.The nucleus lies at the centre of its cell body.The choanocytes use for feeding and for ensuring the flow of water with the animal body.
MESENCHYMES-In between the pinacoderm and choanoderm there is secreated matrix of gelatinous protein that contain several types of freely wandering amoeba like cells or amoebocytes and the skeletal elements of calcium carbonate called as spicules or sclerites
a>AMOEBOCYTES-The larged sized amoebocytes with blunt pseudopodium and large nucleus are the archaeocytes.These contain much RNA .The archaeocytes are self-replacting and also capable of giving rise to all other types of amoebocytes.They give rise to additional pinnacocytes and choanocytesto the collencytes to the scleroblastsor sclerocytes and to the reproductive cells. The archaeocytes carry on all the functions essential for the life of the sponge.
b>SPICULES-These skeletal elements are small or large formed of crystalline calcium carbonate.The needle like spicules are monaxons.Whilesome tetraxons secondarily become triradiate due to loss of one ray.The spicules remain embedded within the mesenchyme.All spicules orient in the same direction.
PINACODERM- It consist of thin and flat polygonal cells, the pinacocytes .It help in the protection to the body.The pinacocytes are hexagonal in surface with thin margin and a bulging central part containing a nucleus. The margin contractility so that the sponge can increage or decrease slightly in size.In the body wall are special large and tubular cells called the porocytes. They are supused to be a modified tubular pinacocytes. Each porocyte contains a central like space,communicating with the outside as well as the spongoel. These spaces are called the ostia or dermal pores or incurrent pores. These help water to flow from outside into the spongoel.
CHOANODERM- The choanoderm cells are also called gastrodermis.It consist of a single layer of flagellated cells the choanocytes.The choanocyte consist of an ovoid cell with free end bearing a transparent contractile collar.The collar surrounds a single long flagellum which arises long flagellum from basal granule.The nucleus lies at the centre of its cell body.The choanocytes use for feeding and for ensuring the flow of water with the animal body.
MESENCHYMES-In between the pinacoderm and choanoderm there is secreated matrix of gelatinous protein that contain several types of freely wandering amoeba like cells or amoebocytes and the skeletal elements of calcium carbonate called as spicules or sclerites
a>AMOEBOCYTES-The larged sized amoebocytes with blunt pseudopodium and large nucleus are the archaeocytes.These contain much RNA .The archaeocytes are self-replacting and also capable of giving rise to all other types of amoebocytes.They give rise to additional pinnacocytes and choanocytesto the collencytes to the scleroblastsor sclerocytes and to the reproductive cells. The archaeocytes carry on all the functions essential for the life of the sponge.
b>SPICULES-These skeletal elements are small or large formed of crystalline calcium carbonate.The needle like spicules are monaxons.Whilesome tetraxons secondarily become triradiate due to loss of one ray.The spicules remain embedded within the mesenchyme.All spicules orient in the same direction.
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