Gut‐associated lymphoid tissue (GALT) of the goldfish, Carassius auratus

Abstract

The head kidney and spleen are major sites of haemopoiesis in fish; a secondary center is found in loose connective tissue of the intestine. In this study we determined the nature of gut-associated haemopoietic tissue in the goldfish, Carassius auratus, using light and electron microscopy. This tissue is a loose stroma of reticular cells and fibers vascularized by capillaries, venules, and arterioles. The cellular population includes lymphoblasts, small and medium-sized lymphocytes, plasmocytes, macrophages, and various granulocytes. The most abundant granulocyte is the mast cell, whose large granules stain with Alcian blue and toluidine blue. Heterophils are found in the intestinal connective tissue as well as two other granulocytes: one with ovoid granules having dense parallel lamellae and another with granules containing crystalline inclusions. Immature forms of both granulocytes were also noted. Macrophages containing phagocytosed debris were often located close to the epithelium; they were observed forming clusters with lymphocytes. The epithelium contained a number of migrating leucocytes including lymphocytes and lymphoblasts, macrophages, and heterophils. Although many granulocytes were found in the connective tissue, granulopoiesis does not seem to be a major function. Gut-associated haemopoietic tissue in goldfish resembles diffuse lymphoid tissue and may be involved in intestinal immune responses.

Anatomia e histologia gastrintestinal da garoupa-verdadeira Epinephelus marginatus (Lowe, 1834) (Teleostei, Serranidae)

“…Em algumas espécies de teleósteos tem sido descrito um tipo especial de leucócito com granulações grosseiras e com afinidade ao corante eosina, cuja função não se encontra devidamente esclarecida. Esse tipo celular tem sido denominado de célula granular (CG) (AL HUSSAINI, 1946), célula de grânulos eosinófilos (EZEABOR; STROKE, 1980), heterófilos (TEMKIN; McMILLAN, 1986) e, atualmente, célula granulocítica especial (CGE). Esse leucócito pode ser localizado em órgão e tecidos distintos em diferentes espécies.…”

Stromal Cells, Macrophages and Lymphoid Cells in the Head-kidney of Sea Bass (Dicentrarchus labrax L.). An Ultrastructural Study.

“…They are agranular cells like those of some fish species (WEINBERG et al, 1972;FERGUSON, 1976;HIGHTOWER et al, 1984;. Granular lymphocytes have been described in Ictalurus punctatus, Cyprinus carpio and Carassius auratus (CANNON et al, 1980;TEMKIN and MCMILLAN, 1986;BIELEK,1988). The scarce, large mitochondria characteristic of some teleost lymphocytes (FERGUSON, 1976;CANNON et al, 1980) are also present in sea bass.…”

“…Fish lymphocytes have also been usually classified into large and small cells (TOMONAGA et al, 1973;LEWIS et al, 1978;BARBER et al, 1981;SAVAGE, 1983;TEMKIN and MCMILLAN, 1986). These may be two different functional stages of the same cell type (ELLIS, 1977), or two separate cell populations with different functional properties (PARROT and DESOUSA, 1971).…”

Histamine is stored in mast cells of most evolutionarily advanced fish and regulates the fish inflammatory response

“…Several reports have described numerous granular cells in the intestinal mucosa, dermis, and gills of many teleost fish families, such as salmonids (10,11), cyprinids (12,13), and erythrinids (2,14). In contrast, other studies have failed to find granular cells in the same tissues of other fish species (4) or have observed only very few granular cells (15,16).…”