Occurrence of lymphohaemopoietic tissue in the meninges of the stingray Dasyatis akajei (Elasmobranchii, Chondricthyes)

Abstract

The cytoarchitecture of the lymphohaemopoietic masses occurring in the "meninx primitiva" of the stingray Dasyatis akajei (Elasmobranchii, Chondricthyes) has been analyzed by light and scanning and transmission electron microscopy. Lymphohaemopoietic aggregates showing similar morphologies occurred along all the central nervous system, but they were more frequent in the telencephalon, diencephalon, and mesencephalon. In each aggregate, the granulopoietic tissue appeared in a fibroblastic stroma surrounding the large blood vessels, and the lymphoid components were present in a reticular network. Developing and mature eosinophils and heterophils--as well as lymphocytes, monocytes, macrophages, and plasma cells--are the main free cells present in these meningeal aggregates. The remarkable intimate association between macrophages and lymphoid cells to form close cell clusters suggests some immunological capacity for the meningeal lymphohaemopoietic tissue. According to their capacities, presence of lymphoid tissue, and histological organization, the meningeal lymphohemopoietic aggregates of Dasyatis akajei resemble other lymphomyeloid aggregates associated with cranium and choroid plexuses in Holocephali and Ganoidei. The phylogenetical relationships of these aggregates with mammalian bone marrow are discussed.

Macrophage‐lymphocyte cell clusters in the hypothalamic ventricle of some elasmobranch fish: Ultrastructural analysis and possible functional significance

“…On the other hand, apart from their evident haemopoietic capacity, no information is available about the functional capabilities of all these tissues. Our current results suggest however, that macrophage-lymphocyte cell clusters found by accident in the floor of third brain ventricle of some specimens of different elasmobranch fish represent groups of lymphoid cells originating in the meningeal lympho-haemopoietic tissue previously described in the stingray Dasyatis akajei (Chiba et al, 1988) and confirmed by the current results.…”

“…Ten years ago, it was proposed (Bjerring, 1984;Fange, 1984) that extinct Devonian placoderms had a meningeal lympho-haemopoietic tissue equivalent to that found in the cranial cavity of Holocephali (Stahl, 1967;Mattisson and Fange, 1986;Mattisson et al, 1990). This hypothesis was indirectly confirmed later when we found such lympho-haemopoietic tissue in the "meninx primitiva" of the stingray Dasyatis akajei (Chiba et al, 1988). Moreover, in other fish, including the elasmobranch Pristiurus (Vialli, 1933) and both Chondrostei and Holostei (Chandler, 1911;van der Horst, 1925;Tilney, 1927;Vialli, 1932;Scharrer, 1944), as well as in the urodeles Ambystoma (Dempster, 1930) and Megalobatrachus japonicus (Sano and Imai, 1961) lympho-haemopoietic tissue is present in association with both meninges and choroid plexuses.…”

“…cally equivalent to the mammalian bone marrow are found in different organs (Zapata and Cooper, 1990). In elasmobranchs, with Holocephali the most primitive vertebrates containing true lymphoid organs, these bone marrow equivalents occur in the Leydig's and epigonal organs, but are also associated with the primitive meninges, throughout the central nervous system (Vialli, 1933;Chiba et al, 1988). This supports Fange's assumption that certain extinct Devonian fishes contained meningeal lympho-haemopoietic tissue (Bjerring, 1984;Fange, 1984).…”

In vivo exposure of clearnose skates, Raja eglanteria, to ionising X-radiation: Acute effects on the peripheral blood, spleen, and epigonal and Leydig organs

“…In the clearnose skate, Raja eglanteria, the molecular evidence for BME tissues is not clearly defined with the expression pattern of RAG1 found in many tissues including Leydig and epigonal organs and thymus in embryonic animals [6]. Other locations in elasmobranchs have been identified as potential BME tissues including meninges of the telencephalon, diencephalons, and mesencephalon of the red stingray, Dasyatis akajei [7]. The kidney has been reported to contain haematopoietic cells in embryos of the small-spotted catshark, Scyliorhinus canicula [8,9].…”

The Adult Hematopoietic Niches — Cellular Composition, Histological Organization and Physiological Regulation

“…The brain and cranium are also suitable sites for haematopoiesis. It occurs in the meninx primitive of some elasmobranches [139] and in the orbit and subcranium of the holocephali, Chimaera monstrosa [140,141]. An analogous tissue occurs in the meninges of ganoids [142] and in the brain of the urodeles Ambystoma [143] and Megalobatrachus japonica [144].…”