Dermal ostia. Three different compositions of cells in sycon 2022-10-24
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A contract is a legally binding agreement between two or more parties that sets out their rights and obligations towards each other. When one party fails to fulfill their obligations under the contract, it can give rise to a legal dispute. In such cases, the parties may seek resolution through the courts, which will apply contract law principles to determine the outcome of the case.
One example of a contract law case study is the case of Carlill v. Carbolic Smoke Ball Co. In this case, the Carbolic Smoke Ball Co. advertised a product called the "Carbolic Smoke Ball" that they claimed could cure influenza and other diseases. The company claimed that they would pay a reward of £100 to anyone who contracted any of the advertised diseases after using the smoke ball according to the instructions.
Mrs. Carlill purchased a smoke ball and used it as instructed, but subsequently contracted influenza. She then claimed the £100 reward, but the Carbolic Smoke Ball Co. refused to pay. Mrs. Carlill brought a legal action against the company, and the case eventually made its way to the Court of Appeals.
The Court held that the advertisement for the smoke ball constituted an offer that could be accepted by anyone who fulfilled the conditions specified in the advertisement, namely using the smoke ball according to the instructions. Mrs. Carlill had accepted the offer by purchasing and using the smoke ball, and the Carbolic Smoke Ball Co. was therefore bound by the contract. The Court ordered the company to pay Mrs. Carlill the £100 reward.
This case illustrates several important principles of contract law, including the concept of an offer and acceptance, the requirement of consideration (i.e., something of value being exchanged between the parties), and the binding nature of a contract once it has been formed. It also shows the importance of clearly stating the terms and conditions of a contract, as the Carbolic Smoke Ball Co. learned the hard way when they were unable to avoid their obligations under the contract despite their initial refusal to pay the reward.
Porokeratotic eccrine ostial and dermal duct naevus
Cell Arrangement and Types of Cells Being some of the simplest animals on the planet, members of the phylum Porifera only have a few different types of cells. Types of Canal Systems Most sponges have one of three types of canal systems: asconoid, syconoid, or leuconoid Figure 12-5. These cells are motile and are involved in several important functions including secreting sponge skeleton and removal of debris etc. Freshwater sponges are most commonly found in midsummer, although others may be more easily found in the fall. · Leucosolenia has the asconoid type of canal system. The third and most common type is the leuconoid system where the choanocytes occupy distinct chambers; examples include Euspongia and Leuconia. They capture small crustaceans with filaments which stick to their shells like Velcro.
The edges of these cells are characterized by wavy contours which enhance The inner part, on the other hand, consists of specialized cells known as choanocytes. Depending on the species, fertilization may be internal or external. Pinkish radioles of a Christmas tree worm, Spirobranchus giganteus phylum Annelida, class Polychaeta also project from the coral colony. In some species, sperm enter a different sponge body where they are captured and transferred to cells, which then travel through the tissue to an embedded egg. Have six-rayed, siliceous spicules extending at right angles from a central point; spicules often united to form network; body often cylindrical or funnel shaped; flagellated chambers in simple syconoid or leuconoid arrangement; habitat mostly deep water; all marine. .
Monoaxon spicules are found in A. Dermal ostia B. Gastrial ostia C. S
Figure 12-13 A, Development of demosponges. There are rare cases of extensive lesions affecting large parts of the body. Form and Function Sponges feed primarily by collecting suspended particles from water pumped through internal canal systems. The body surface of the asconoid type of sponges is pierced by a large number of minute openings called as incurrent pores or ostia. Asconoids Asconoid sponges have the simplest organization. Some, called sclerocytes, secrete spicules.
This connects the flagellated chambers with the excurrent canals. So-called bath sponges Spongia, Hippospongia belong to the group called horny sponges, which have spongin skeletons and lack siliceous spicules entirely. When conditions improve, there is a rapid generation of all cell types as the organism becomes more active. These canals open into the central spongocoel by internal ostia or apopyles. From the water, the Nutrition - Members of the phylum Porifera are filter feeders.
Phylum Porifera: Canal System in Sponges, Types of Canal Systems in Sponges
· Presence of paragastric cavity or spongocoel. Bath sponges have spongin skeletons and lack siliceous spicules altogether. Gemmules are a mechanism for survival of the harsh conditions of winter. Unlike most animals, the majority of sponges are asymmetrical. Electron microscopy shows that the collar is made up of adjacent microvilli, connected to each other by delicate microfibrils, forming a fine filtering device for straining food particles from water Figure 12-10B and C.
Water flow is very directed. However, ciliated cells are suspected to play an important role in sensing any form of disturbance. Sessile animals make few movements and therefore need little in the way of nervous, sensory, or locomotor parts. Most marine sponges are brightly colored due to pigments in their dermal cells. Choanocytes not only keep the water moving but also trap and phagocytize food particles that are carried in the water. Also, collar cells are found in certain corals and echinoderms, so they are not unique to the sponges.
However, some of the species are capable of changing sexes from male to female and vice versa e. Canal system in sponges· This system helps in nutrition, respiration, and excretion. Class Calcarea Calcispongiae Calcarea also called Calcispongiae are calcareous sponges, so called because their spicules are composed of calcium carbonate. Pinacocytes The nearest approach to a true tissue in sponges is arrangement of the pinacocyte cells of the pinacoderm Figure 12-9. Three types of sponge structure.
Triaxons - Also known as hexactinal spicules, triaxons consists of three axes that cross at right angles resulting in a structure with six rays. · Spicules of Leucosolenia are made up of calcium carbonate, secreted by calcoblasts. Other sponges are oviparous, and both oocytes and sperm are expelled into the surrounding water. The larval stage is known as Amphiblastula Sycon or Parenchymula Leucosolenia. However, many zoologists opposed that hypothesis because sponges do not acquire collars until later in their embryological development.
These incurrent pores open into incurrent canals. The leuconoid type is considered the major plan for sponges, for it permits greater size and more efficient water circulation. Thesocytes Store food · Myocytes form sphincters around the Osculum and Ostia. Common coloration of sponges are those of the rainbow such as yellow, orange, green, red, and purple. As the choanocytes filter the water and extract food particles from it, used water is expelled through a single large osculum. · Fertilization is internal. This leuconoid grade has evolved independently many times in sponges.