American paddlefish leukocytes demonstrate mammalian‐like cytochemical staining characteristics in lymphoid tissues

Abstract

American paddlefish Polyodon spathula leukocytes demonstrated cytoplasmic staining patterns very similar to mammalian leukocytes when stained with acid phosphatase, a-naphthyl butyrate esterase and b-glucuronidase. American paddlefish monocytes, lymphocytes and granulocytes stained positive for acid phosphatase. Monocytes stained positive for a-naphthyl butyrate esterase. Lymphocytes that stained positive for a-naphthyl butyrate esterase were designated type A. Lymphocytes that stained positive with antibodies to the L chain of white sturgeon Acipenser transmontanus immunoglobulin (Ig) were designated type B. Type A and type B lymphocytes stained positive for b-glucuronidase. All leukocytes observed were negative for Sudan Black B. Monocytes, lymphocytes and granulocytes were present in the renal haematopoietic tissue, spleen, thymus, pericardial myeloid tissue, lamina propria of the spiral valve, and in meningeal myeloid tissue located dorsal to the brain, at the base of the brain and around the notochord. Peyer's patches were present in the gut. Morphological characteristics of leukocytes stained with Wright's and haematoxylin and eosin and appeared very similar to those of other fish species. # 2005 The Fisheries Society of the British Isles

The first finding of Hassall's corpuscles in the thymi of cultured sturgeons

“…Histologically, the thymus is lobulated and organised in the outer cortex enclosing the central medulla (Petrie-Hanson and Peterman 2005). A diversity of different cell types is found within the thymus.…”

“…The cortex is predominantly composed of closely packed lymphocytes. The medulla is composed of sparsely organised lymphocytes, macrophages, reticular cells and Hassall's corpuscles that have a disperse distribution (Fange 1986;Petrie-Hanson and Peterman 2005;Peterman and Petrie-Hanson 2006). …”

Ontogeny of American paddlefish lymphoid tissues

“…There are minimal histological differences between vertebrate thymus. The juvenile paddlefish thymus is lobulated and differentiated into cortical and medullary areas (Petrie‐Hanson & Peterman, 2005), as is the condition in the sturgeon (Fange, 1986), elasmobranchs (Zapata & Cooper, 1990), and mammals (Burkitt et al ., 1993). In other fishes, however, the thymus is not lobulated.…”

“…In other fishes, however, the thymus is not lobulated. Hassall’s bodies were not observed in the paddlefish thymus viewed in this study, but have been reported in light microscopy studies of thymic tissues from older paddlefish (Good et al ., 1966; Petrie‐Hanson & Peterman, 2005). In the elasmobranch thymus, epithelial cells containing masses of degenerated fibrous material resembling the keratin bundles found in the unicellular Hassall’s bodies of mammalian thymus have been observed (Zapata et al ., 1996).…”

“…Paddlefish were spawned artificially and reared as described previously (Petrie‐Hanson & Peterman, 2005). Eggs were incubated and fry were maintained in 15° C well water.…”