Amoebocyte

A type of cell found in invertebrates, involved in various functions including defense and nutrient transport

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Amoebocyte
Kingdom:
Phylum:	Arthropoda
Class:	Merostomata
Order:	Xiphosura
Family:	Limulidae

An amoebocyte is a type of cell found in the bodies of various invertebrates, including sponges, cnidarians, echinoderms, and arthropods. These cells are characterized by their amoeba-like movement, which allows them to move through the organism's body fluids or tissues. Amoebocytes play crucial roles in the immune response, nutrient transport, and other physiological processes.

Functions

Amoebocytes are involved in several key functions within invertebrate organisms:

• Defense and Immunity: Amoebocytes are part of the invertebrate immune system. They can engulf and digest foreign particles, bacteria, and dead cells through a process known as phagocytosis. In horseshoe crabs, amoebocytes are responsible for the clotting of blood and the encapsulation of pathogens.

• Nutrient Transport: In sponges, amoebocytes transport nutrients from the choanocytes, which capture food particles, to other cells within the sponge. They also distribute oxygen and remove waste products.

• Reproduction: In some species, amoebocytes are involved in the formation of gametes or in the development of reproductive structures.

• Structural Support: Amoebocytes can secrete spicules or spongin fibers, which provide structural support to the organism, particularly in sponges.

Types of Amoebocytes

Amoebocytes can be classified into different types based on their function and morphology:

• Archaeocytes: These are totipotent cells found in sponges that can differentiate into other cell types, including those involved in reproduction and nutrient transport.

• Sclerocytes: These cells are responsible for the secretion of spicules in sponges, contributing to the structural framework of the organism.

• Lophocytes: These cells secrete collagen fibers, which are important for the sponge's structural integrity.

• Granulocytes: Found in horseshoe crabs, these cells contain granules that release substances involved in the immune response.

Significance in Research

Amoebocytes, particularly those from horseshoe crabs, have significant applications in biomedical research. The Limulus Amebocyte Lysate (LAL) test, derived from horseshoe crab amoebocytes, is widely used to detect bacterial endotoxins in medical equipment and pharmaceuticals.

Also see

• Phagocytosis
• Invertebrate immune system
• Limulus Amebocyte Lysate
• Sponge anatomy