THE LYMPHOMYELOID (HEMOPOIETIC) SYSTEM OF THE ATLANTIC NURSE SHARK,GINGLYMOSTOMA CIRRATUM

Abstract

The lymphomyeloid system of nearly adult nurse sharks, Ginglymostoma cirratum, was investigated. Lymphomyeloid structures detectable by the naked eye at dissection are the epigonal organ and the spleen. Microscopic examination shows that the epigonal organ produces granulocytes and lymphocytes. The white pulp of the spleen is lymphoid, whereas the red pulp is mainly erythropoietic. Cells with the morphological characteristics of plasma cells occur in the epigonal organ and the spleen. Peroxidase-positive granulated cells are found in the epigonal organ. In contrast to many other elasmobranchs, the nurse shark lacks the Leydig organ, i.e. the lymphomyeloid structure of the esophagus; but the epigonal organ is well developed and averages 0.60% of the body weight. The spleen weighs about 0.26% of the body weight. The mode of life of the nurse shark in shallow tropical waters probably puts a considerable demand on its immune system. Cells produced by the epigonal organ may be important in immune responses and in inflammatory processes.

The enzyme cytochemistry of leucocytes in blood and haematopoietic tissues of holocephalans (Chondrichthyes: Chimaeriformes)

“…The enzyme cytochemistry of holocephalan granulocytes also shows features of agnathans and elasmobranchs. The weak peroxidase in granulocytes of one holocephalan species is consistent with the conflicting reports on holocephalans (Mitsui 1965;Johansson 1973) and elasmobranchs (Mitsui 1965;Fey 1966;Johansson 1973;Grimaldi et al 1983;Mainwaring & Rowley 1985) although a strong peroxidase reaction has been illustrated in epigonal granulocytes of one elasmobranch (Fange & Mattisson 1981). The heterophils or neutrophils of most bony fishes and of higher vertebrates are peroxidase-positive (Mitsui 1965).…”

“…Elasmobranchs have two lymphomyeloid organs, the epigonal organ in close association with the gonads (Fange & Mattisson 1981;Honma et al 1984) and Leydig's organ in the lining of the oesophagus (Mattisson & Fange 1982). All elasmobranchs have one or both organs (Honma et al 1984) which are the site of granulopoiesis and lymphopoiesis, whereas thrombopoiesis and erythropoiesis occur in the spleen (Pulsford et al 1982).…”

“…Although elasmobranch leucocytes have been subject to limited ultrastructural (Morrow & Pulsford 1980;Fange & Mattisson 1981;Mattisson & Fange 1982;Pulsford et al 1982;Honma et al 1984) and a few cytochemical studies (Mitsui 1965;Fey 1966;Johannson 1973;Grimaldi et al 1983;Mainwaring & Rowley 1985), holocephalan blood has only been examined using Romanovsky stains at the light microscope level (FSnge & Sundell 1969). This study examines the leucocyte enzymes of six holocephalan species and is related to concurrent studies on holocephalan granulocyte ultrastructure (Hine & Wain 1988) and elasmobranch ultrastructure (Hine & Wain 1987a, 1987b, 1987c and enzyme cytochemistry (Hine & Wain 1987d).…”

Antibacterial Proteins and Peptides in Nurse Shark (<em>Ginglymostoma Cirratum</em>) Peripheral Blood Leukocytes

“…In sharks, the site of hematopoiesis (i.e., formation of erythrocytes and leukocytes) is the epigonal organ (a part of its reproductive system), a lymphoid organ, and the spleen (Fange 1977;Fange et al 1981;Zapata 1981). Since cell lysates prepared from shark peripheral blood leukocytes show significant antibacterial activity, it is reasonable to assume that the factors responsible for this activity are most likely associated with the shark neutrophil and/or eosinophil as well as the monocyte-macrophage, an active phagocytic cell.…”

“…Nurse sharks inhabit tropical and subtropical waters on the continental shelf, and can be found along the Western and Eastern Atlantic coasts; along the islands of the Caribbean; as well as the Eastern Pacific coast. Nurse sharks have been known to inhabit polluted waters, as they are bottom dwellers of shallow warm waters (Fange et al 1981). In this environment the nurse shark is at a greater risk to infectious agents than animals that inhabit deeper and more open waters (which are less likely to be polluted), and runs a greater risk of physical trauma as a result of man's intrusion into its habitat (Reif 1978).…”