The Thymic Microenvironment of the Common Sole, Solea solea

Abstract

The thymus of the sole Solea solea contained lymphoblasts and thymocytes within a network of pale and dark epithelial cells. The pale cells were characterized by tonofilaments and desmosomes and some embraced rodlet cells within their cytoplasmic processes. The dark epithelial cells had numerous electron‐dense inclusions and electron‐lucent vacuoles. Lymphocytes were closely associated with the plasma membrane of both types of epithelial cells and with macrophages. Breakdown of effete lymphocytes appeared to be the main function of the macrophages. Some macrophages were multinucleated. Those containing melanin granules associated with phagosomes were classified as melanomacrophages. Pigment cells including melanophores and guanophores were present along the connective tissue trabeculae and surrounding the blood vessels. A few plasma cells and mucous cells were present.

In Vitro and In Situ Characterization of Fish Thymic Nurse Cells

“…On the other hand, our in situ electron microscopy study confirms previous results (Pulsford et al, 1991;,lvarez, 1993) (Kyewski and Kaplan, 1982;Kaneshima et al, 1987;Mizutami et al, 1987) and medullar epithelium has also been mentioned (Hugo et al, 1988 (Zapata, 1981;Castillo et al, 1990Castillo et al, , 1991. It is, however, difficult, from a merely morphological study, to establish correlations between the in vitro isolated TNCs and these lymphocyte-epithelial-cell clusters identified in situ.…”

“…On the other hand, our in situ electron microscopy study confirms previous results (Pulsford et al, 1991;,lvarez, 1993) (Penninger et al, 1994). Nevertheless, the TCR-MHC interactions are apparently not necessary for the formation of mouse TNCs (Boyd et al, 1993) …”

“…In Rana pipiens tadpole thymi, Holtfreter and Cohen (1987) between the epithelial cells and thymocytes (Pulsford et al, 1991;lvarez, 1993), whereas thymocyte-macrophage complexes have been reported in both elasmobranches (Pulsford et al, 1984;Navarro, 1987) and teleosts (Finge and Pulsford, 1985).…”

“…They have been involved in the establishment of positive (Farr and Anderson, 1985;Kyewski, 1986;Owen et al, 1986;Ron et al, 1986) and negative selection (Wick and Oberhuber, 1986;Lorenz and Allen, 1989;Speiser et al, 1992), although their formation is not dependent on TCR-MHC interaction (Boyd et al, 1993;Aguilar et al, 1994 between the epithelial cells and thymocytes (Pulsford et al, 1991;lvarez, 1993), whereas thymocyte-macrophage complexes have been reported in both elasmobranches (Pulsford et al, 1984;Navarro, 1987) and teleosts (Finge and Pulsford, 1985).…”

Immunocytochemical detection of Ig-positive cells in blood, lymphoid organs and the gut associated lymphoid tissue of the turbot (Scophthalmus maximus)

“…To provide a clear distinction between surface Ig-bearing cells (sIg + ) and cells containing cytoplasmic Ig (cIg + ), and thus determine if all B cells were detected, a test was carried out using unfixed and fixed blood cell suspensions. For detection of surface antigens, unfixed smears must be used immediately while for intracellular antigen detection, it is necessary to fix smears with methanol (Brandtzaeg, 1982 (Zapata, 1981;Pulsford et al, 1991). In rainbow trout, using a specific anti-IgM monoclonal antibody, it was shown that a small population of thymocytes reacted (DeLuca et al, 1983) and more recently results obtained in sea bream (Navarro et al, 1993) and sea bass (Romestand et al, 1995) confirmed these data.…”