Polyp: Definition, Types, and Examples

  • Post last modified:November 6, 2021
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Polyp Definition

Polyp is a word that has multiple meanings in biology. It can refer to a stage in the development of some invertebrates, or it can relate to the growth of organ tissues.

Polyps as a Life Cycle

Cnidarians, such as jellyfish, anemones, and coral, have nematocysts on the surface of their tentacles. These tiny explosive cells are employed to transmit poison to the prey or to attach to it. It is possible to consume the prey once it has been captured.

Nematocysts are found in all cnidarians, and many of them are polypoid, while some are not. Planula, or small, free-swimming larvae, are the starting point for these tiny creatures.

When two coral gametes encounter in the open water, these larvae develop. The larvae migrate away from the parents in order to start new colonies. When a planula comes across a hard surface with lots of nutrients in the surrounding water, it can grow into a polyp and start a new colony.

The overall arrangement of polyps in most species is the same. A polyp adheres to a hard surface using a specific tissue called the pedal disc on the bottom.

The stalk, which extends away from the pedal disc, keeps the mouth and tentacles suspended in the water column. These tentacles filter food from the surrounding water and bring it to the mouth of the polyp. By budding apart, the polyps can reproduce asexually. Large coral structures are created in this manner.

When the corals are ready to reproduce sexually, they discharge their gametes into the water column. New planula larvae will develop when the gametes unite, and they will look for new locations to colonise.

Sea anemones, which belong to the same Anthozoa class as sea anemones, spend the bulk of their life in a polyp form. Sea anemones, while considerably larger than individual coral polyps, function in the same way.

The anemone is attached to a hard surface by a pedal plate, and its tentacles capture food and transfer it to the mouth. Many nematocysts are found on each tentacle, which can hurt and paralyse passing animals.

Coral polyps and sea anemones both reproduce in the same way. They exist as polyps that produce gametes that develop into new larvae capable of conquering new territory.

Asexual reproduction is also possible, with the polyp budding out tiny fragments that can grow into complete anemones. Other cnidarians, such as jellyfish, have a polyp stage as well.

The medusa stage is the most common type of free-swimming jellyfish. Jellyfish polyps resemble those of coral and anemones, but instead of gametes, they produce the medusa stage.

After that, the medusas grow and discharge gametes. Once fertilised, the gametes develop into a planula larva, which then develops into a polyp.

Scyphistoma, or jellyfish polyps, produce tiny medusa and discharge them as they mature. Some jellyfish lack a polyp stage, and the larvae grow into another medusa right away.

Polyps as a Medical Condition

In medical terms, a polyp is an overgrowth of organ tissue. Some tissue polyps have a small stalk that connects them to the mucous membrane, similar to invertebrates. Medical polyps, unlike invertebrate polyps, are not separate creatures.

Instead, they’re caused by some tissue developing quicker than the surrounding tissue. The colorectal polyp is a common kind of polyp that can be seen in many people. These polyps are usually non-cancerous and do not pose a threat to health.

These tiny growths can be removed during a normal colonoscopy to reduce the risk of their becoming cancerous. Malignant neoplastic tissue can form large, aberrant polyps.

These polyps will develop and mix with the surrounding tissues to form a tumour. Polyps are frequently discovered by the extra bleeding they produce in the tissues they originate in, whether cancerous or not.

A blood test that shows increased amounts of specific proteins, which suggest internal bleeding, can identify their existence.

What Causes Polyps?

Polyps can develop from a variety of sources. Polyps are formed when cell division is disrupted, much like malignant cells. DNA damage, tissue inflammation, or any other stress on the cell that promotes accelerated cell division might be the source of the dysregulation.

An increase in polyps or an early start of polyps can be caused by a variety of hereditary disorders. Carcinogens in the environment may potentially induce genetic alterations.

Carcinogens are chemicals that can alter DNA, resulting in accelerated cell division and the formation of polyps. Other polyps, such as nasal polyps, might be produced by allergies’ repeated irritation. Inflammation induced by drug usage or exposure to hazardous substances might potentially develop polyps.

Medusa is a free-swimming mammal that may also be found as polyps adhering to the seabed. The overall shape of a polyp is a polypoid, which is made up of an upside-down bell linked to a stalk.

Hyperplasia is a disorder in which a region of the body has an excessive number of cells. Any clump of cells that has grown too big or out of place, including polyps, is referred to as a tumor.

Polyps Citations
  • Mesodermal anatomies in cnidarian polyps and medusae. Int J Dev Biol . 2006;50(7):589-99.
  • Sex, polyps, and medusae: Determination and maintenance of sex in cnidarians. Mol Reprod Dev . 2017 Feb;84(2):105-119.
  • Will we ever cure nasal polyps? Ann R Coll Surg Engl . 2019 Jan;101(1):35-39.
  • Uterine polyps, adenomyosis, leiomyomas, and endometrial receptivity. Fertil Steril . 2019 Apr;111(4):629-640.
  • Chronic Rhinosinusitis with Nasal Polyps. J Allergy Clin Immunol Pract . Jul-Aug 2016;4(4):565-72.
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