Growth of the lymphoid organs in Rainbow trout, Salmo gairdneri from one to fifteen months of age

Abstract

The growth and cellular composition of the thymus, spleen and kidney were monitored in Rainbow trout, Salmo gairdneri, from 1 to 15 months of age. All organs grew as the fish grew, but they attained their maximum relative weights (expressed as a percentage of body weight) at 2–3 months ofage. The organ weights showed a closer correlation to body weight than they did to age. The total number of leucocytes in the lymphoid organs increased with age; however, the number per gram of lymphoid organ tissue, and per gram of tissue per gram of fish, decreased with age. The number of cells present showed a closer correlation to the weight of their respective organ, than they did to age. A histological study of the lymphoid organs showed gradual changes in the structure of the lymphoid tissues. The thymus showed some signs of involution even at 15 months of age. The spleen and kidney had mixed populations of erythrocytes and leucocytes, with a gradual increase in the amount of melanin as the fish aged. The kidney in particular had a rich variety of leucocytes. The blood picture showed no obvious fluctuations with age or season over the period studied, with the proportion of lymphocytes present remaining remarkably constant.

Exogenous 17β‐oestradiol (E2) modifies thymus growth and regionalization in European sea bass Dicentrarchus labrax

“…These observations underscore the highly dynamic nature of the thymus (Dooley & Liston, 2012). Similar transitions in the thymus volume during development have also been reported in rainbow trout Oncorhynchus mykiss (Walbaum, 1792) (Grace & Manning, 2010). The reduction in organ volume towards 239 dph is possibly explained by the release of mature T-cells that leave the thymus at the end of the first maturation wave.…”

Thymus development in the zebrafish (Danio rerio) from an ecoimmunology perspective

“…However, as shown by the present study and by Lam et al (2002), expansion and rapid growth of the thymus takes place only during the juvenile period of zebrafish. This thymus development pattern appears to be more generally realized in teleost fish, with the thymus being the first lymphoid organ to differentiate morphologically (Davidson & Zon, 2004;Rombout et al, 2005;Seemann et al, 2015;Zapata et al, 2006) and becoming only functional in the juvenile period (Falk-Petersen, 2005;Hunt & Rice, 2008;Lam et al, 2004;Mulero et al, 2007;O'Neill, 1989;Parichy et al, 2009;Tatner & Manning, 1983). This late onset of thymus development and adaptive immune systems appears to be expressed in all teleost species that have been studied to date.…”

Antiparasitic potential of alternative treatments against larval stages of Lernaea cyrpiancea

“…Ten parts per million of it would be su cient to prevent re-infection by the parasite and apparently does not cause deleterious effects to R. quelen fries (LC 50 96h was 16.74 mg L − 1 ), highlighting the potential use of the product as a prophylactic agent. Even so, it is important to point out that early stages of sh development are proven to be more sensitive than advanced stages due to incomplete development of the immune system and lymphoid organs (Ellis 1988;Hrubec et al 2004;Tatner and Manning 1983), which may mean an even greater margin of use of the product in the treatment against L. cypriancea. Barry et al (1995), for example, evaluated the effects of different postclosure periods on the tolerance of Melanotaenia uviatilis larvae Castelnau, 1878 against exposure to a synthetic insecticide used in crop pest control.…”