Renal portal phagocytosis of bacteria in rainbow trout (Salmo gairdneri Richardson): ultrastructural observations

Abstract

Vrterinerry Collcgo, Unr r,or.slty o/ Glic)lph, (;lic)lpll. 0 t r t . , Ccrt~crclcr N 1 G 2 W 1 Received May 3 0 , I984 FERGUSON, H. W. 1984. Renal portal phagocytosis of bacteria in rainbow trout (Strlrno ,qcrircltrt~ri Richardson): ultrastructural observations. Can. J . Zool. 62: 2505 -25 1 I .Catheterized rainbow trout (Salmo guirtlncri) were inoculated with killcd bacteria and the perfuscd-fixed kidney was examined in the electron microscope. The endothelium of the portal circulation was continuous but had evidence of marked pinocytotic activity with large numbers of intracytoplasmic vesicles. many of which were spiny coated. Intracytoplasmic transfer tubules were also a prominent feature. Bacteria were phagocytoscd by macrophages closely associated with the endothelium, but not by the endothelial cells. Macrophage pseudopodia werc occasionally sccn traversing cndothelium to touch the underlying haemopoietic tissue. ' The renal portal vasculature provides a largc area for efficient antigen trapping.

An immunohistochemical study of Flexibacter psychrophilus infection in experimentally and naturally infected rainbow trout (Oncorhynchus mykiss) fry

“…The latter observations were also in agreement with the findings in naturally infected fry, especially in chronically infected fish, where bacteria/bacterial products were detected in melanomacrophages in the kidney and spleen. Earlier studies have demonstrated that injected particulate material (Salmonella bacteria) and soluble particles (carbon) accumulate in melanomacrophages (Roberts 1975, Ellis et al 1976, Ferguson 1984, Tatner & Manning 1985. In addition, it has been suggested that melanomacrophages are composed of accun~ulations of sinusoidal macrophages, that have ingested foreign material and (perhaps) moved into the interstitial tissues (Vogelbein et al 1987, Tsjuii & Seno 1990, Brattgjerd & Evensen 1996.…”

The trapping of intravenously injected extracellular products fromAeromonas salmonicidain head kidney and spleen of vaccinated and nonvaccinated Atlantic salmon,Salmo salarL.

“…The sinusoidal network of the head kidney is lined by endothelial cells that have a prominent role in the clearance of many small particles and soluble molecules . In addition, sinusoidal macrophages (Zapata, 1979;Press et al, 1994) are active in the phagocytosis of many exogenous substances (Ellis et al, 1976;Dannevig et al, 1994) and are shown to be responsible for the clearance of bacteria in salmonids (Ferguson, 1984;Brattgjerd & Evensen, 1996). A. salmonicida antigens were taken up by scattered macrophage-like cells in vaccinated salmon and by endothelial cells lining the sinusoids in nonvaccinated fish.…”

“…In the head kidney *Please address all correspondence to: A. Espenes, Department of Morphology, Genetics and Aquatic Biology, Norwegian College of Veterinary Medicine, Box 8146, 0033 Oslo, Norway. of salmonids, bacteria were phagocytosed by sinusoidal macrophages (Ferguson, 1984;Brattgjerd & Evensen, 1996) whereas the sinusoidal endothelial cells were important in the clearance of small particles and soluble molecules . In the head kidney of carp, Cyprinus carpio L., human gamma globulin complexed with immunoglobulin was taken up more quickly than antigen alone (Secombes et al, 1982).…”

Kinetics of in vitro phagocytosis by cells from head-kidney of common carp, Cyprinus carpio.

“…Large masses of leucocytes of different develop mental stages can be found in the hemopoietic tissues of the kidney and the spleen. These apparently do not take part in the phagocytosis at this location as detected by FERGUSON (1984) in an experiment with rainbow trout, Salmo gairdneri.…”

“…Presence of the juvenile neutrophils in the phagocytosis may be of great importance in certain pathological processes. FERGUSON (1984) demonstrated that the cells in the hemopoietic tissues of rainbow trout are not likely to contact particulate antigens present in the peripheral blood. However, they were stimulated by in traperitoneally injected bacterial antigen in eel (NAGAMURA and WAKABAYASHI, 1984) as shown by the glycogen accumulation in their cyto plasms, a process considered to be an introduc tory step towards eventual functioning.…”