Observations on rodlet cells found in the vascular system and extravascular space of angelfish (Pterophyllum scalare scalare)

In the angelfish (Pterophyllum scalare scalare) numerous rodlet cells were found in the large post‐orbital blood vessel caudal to the eye and in the surrounding extravascular space. Within the vessel the rodlet cells formed striking regular arrays, along the inner aspect of the wall. The rodlets within the cells were positive to PAS but negative to Sudan Black B, Masson's, and the Fuelgen stain. The capsule around the cells was negative for all these stains. These rodlet cells appeared to be traversing the vessel endothelium, and to be pushing the endothelium aside without damaging it. Some discharged their contents into the vessel, but we never observed the release of intact rodlets. The nuclei of rodlet cells in actual contact with the vessel were at the end of the cell more distant from the endothelial wall. Cell‐to‐cell adhesion structures or communications junctions between rodlet cells and the endothelium were not evident. A putative rodlet cell precursor in the extravascular space contained large electron‐dense granules, and extended pseudopodia that contacted nearby rodlet cells. Based on their morphology, tissue distribution, and their behaviour, we conclude that the rodlet cell is an endogeneous teleost cell type, and possibly represents a form of matured granulocyte. Copyright © 1995, Wiley Blackwell. All rights reserved