archaeocytes

Archaeocytes are amoeboid cells embedded in the mesohyl of sponges (phylum Porifera). They are among the most versatile cell types in sponges and are commonly described as totipotent or multipotent. Archaeocytes originate from other cell lineages, such as choanocytes, during growth or regeneration, and can migrate within the mesohyl to sites of injury or new tissue.

Their functions are diverse. They participate in digestion by phagocytosing food particles that have been brought to the mesohyl by choanocytes, and they distribute nutrients to other cells. They also store nutrients in vacuoles and can operate in wound repair and regeneration. A key role of archaeocytes is differentiation: they can give rise to other cell types needed by the sponge, including sclerocytes (which generate siliceous or calcareous spicules), collencytes (collagen-producing cells), and lophocytes (spongin-forming cells). In some species, archaeocytes can differentiate into germ cells and contribute to reproduction.

Archaeocytes are typically large, irregular, amoeboid cells with radiating pseudopodia that allow them to move through the gel-like mesohyl. They are found throughout the mesohyl, and their abundance and activity vary with the sponge’s developmental stage and environmental conditions. Because sponges lack true tissues, archaeocytes play a central role in tissue maintenance, skeleton formation, and nutrient distribution within the organism.

See also: Amoebocytes, Sponge cell types.