Melano‐macrophage centers in the aglomerular kidney of the sea horse (Teleosts): Morphologic studies on its formation and possible function

Abstract

In order to elucidate the process of the formation and possible function of the renal "melano-macrophage centers (MMC)" of fish, light and electron microscopic observations were carried out on the aglomerular kidney of the sea horse, Hippocampus kuda BLEEKER, injected with antigenic horse-spleen ferritin (AF) and nonantigenic carbon particles (CP). Kidneys of the sea horse have well-developed hemopoietic foci in the interstitial tissues surrounding the bundles of renal tubules. Each hemopoietic focus has a small artery in the central area and is framed with the densely arranged sinusoids lined with monolayered macrophages which have no melanin pigments. In the hemopoietic foci free macrophages (M phi) were hardly found, but large clusters of MMC filled with densely packed masses of cell debris with some melanin pigments were encountered. Some of them had degenerated M phi with fibrotic change surrounded by fibroblasts. AF and CP injected intraperitoneally entered quickly into blood vessels and were taken up actively by the sinusoidal M phi. The M phi full of AF or CP left the sinusoidal wall and moved gradually into hemopoietic foci to form the MMC or to fuse with the preexisting MMC. The melanophores in the interstitial connective tissue joined to form the MMC. No specific histologic change suggestive of immune response to the AF was present in and around the MMC. The results indicate that the MMC of fish should be only the aggregates of M phi to digest the ingested materials effectively. The process of formation of MMC and their possible function is discussed.

Cytomorphological alterations of the thymus, spleen, head‐kidney, and liver in cardinal fish (Apogonidae, Teleostei) as bioindicators of stress

“…In the last decade, several studies have exposed links between pollution and health of fishes and other marine organisms (Roberts, 1985;Fournie et al, 2001;Cajaraville et al, 2003). In fishes, according to various authors (Tsuji and Seno, 1990;Fredello et al, 2001), larger aggregations of macrophages or melano-macrophage centers, normally found in the lymphatic and other organs, are involved in various processes of phagocytosis, storage, and detoxification of bacteria and alien materials. Micale and Perdichizzi (1990) demonstrated that increased numbers of melano-macrophage centers in the fish spleen are induced by environmental factors and not only by tissue catabolism.…”

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

“…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 positive imrnunostaining of sinusoidal macrophages most likely reflects the ability of this cell population to phagocytize particulate material, as also observed for latex particles ( S m e d s r~d et al 1993).…”

Conservation of the chromatophore pigment response

“…Fish species are also known to alter their appearance when ill or under stressful and hazardous conditions, by visibly appearing either paler or darker in color (Wallbrunn, 1957). Melanophores in some teleost species even associate with macrophages in hematopoietic tissue to form melanomacrophage centers, and may play a role in host immune defenses (Agius, 1980;Ellis and Munroe, 1976;Roberts, 1975;Tsujii and Seno, 1990). The many physiological functions that chromatophores possess impart the versatility of using these cell types in vitro to sense varying agents.…”