The Holothuria polii brown bodies

Abstract

Holothuria polii brown bodies are associated with the defence mechanisms of the host. Naturally and experimentally induced brown bodies are histologically constituted by nodules in a granular extracellular matrix containing distinct spherule cell types. Nodules of natural brown bodies consist in flattened amoebocytes surrounding large antigens, whereas nodules from experimentally induced brown bodies originate from the aggregation of phagocyting amoebocytes. An extracellular granular matrix characterizes both types of brown bodies. It probably originates from degranulation of spherule cells.

The presence of acid phosphatase and arylsulfatase in the homo‐genate of brown bodies suggests that these structures are able to digest enclosed substances via lysosomes.

Key words:

• Holothurian defence mechanisms
• Brown bodies
• Amoebocytes
• Spherule cells