Ultrastructural characterization of leucocytes in the pronephros of carp (Cyprinus carpio, L.)

Area of Science:

• Ichthyology
• Cell Biology
• Immunology

Background:

• The pronephros in carp (Cyprinus carpio, L.) is a key site for immune cell activity.
• Understanding the cellular composition and function of the pronephros is crucial for fish health and immunology.

Purpose of the Study:

• To ultrastructurally characterize the diverse cell types present in the carp pronephros.
• To investigate the phagocytic activity of these cells against Bacillus megaterium in vitro.

Main Methods:

• Ultrastructural characterization of pronephric cells.
• Separation of cell populations using a Percoll continuous density gradient.
• In vitro phagocytosis assays with Bacillus megaterium.

Main Results:

• Identified erythrocytes, lymphocytes, plasma cells, thrombocytes, granulocytes (neutrophilic, eosinophilic, basophilic), and reticular cells (phagocytic and non-phagocytic).
• Monocytes and neutrophilic granulocytes demonstrated in vitro phagocytosis of bacteria.
• Basophilic and eosinophilic granulocytes showed bacterial engulfment without true endocytotic uptake.

Conclusions:

• Carp pronephros harbors a variety of immune and non-immune cells with distinct ultrastructural features.
• Monocytes and neutrophils are primary phagocytes, while other granulocytes exhibit alternative mechanisms for interacting with bacteria.