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

Torroba, M.; Chibá, Akira; Vicente, Ángeles; Varas, Alberto; Sacedón, Rosa; Jiménez, Eva; Honma, Yoshio; Zapata, A.

doi:10.1002/ar.1092420312

Cited by 12 publications

(6 citation statements)

References 27 publications

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“…No fishes possess bone marrow. Haematopoiesis takes place at other sites including the liver and spleen (Hyder et al, 1983;Tavassoli, 1986;Torroba et al, 1995). Both elasmobranch and teleost fishes possess erythrocytes, several types of lymphocyte and monocytemacrophages (Hyder et al, 1983;Ellis, 1986).…”

Section: Discussionmentioning

confidence: 99%

The cartilaginous skeleton of an elasmobranch fish does not heal

Ashhurst

2004

Matrix Biology

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Section: Discussionmentioning

confidence: 99%

The cartilaginous skeleton of an elasmobranch fish does not heal

Ashhurst

2004

Matrix Biology

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“…Also like Xenopu. 5, GC have not been detected in sharks although lymphocyte aggregations which may be associated with local immune responses have been identified (42).…”

Section: Antigeti-dependent Mutation In Ectotherinic Vertebratesmentioning

confidence: 99%

Evolution of somatic hypermutation and gene conversion in adaptive immunity

Diaz

Flajnik

1998

Immunological Reviews

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Examples of somatic hypermutation of antigen receptor genes can be seen in most lineages of vertebrates, including the cartilaginous fish. Analysis of the phylogenetic data reveals that two distinctive features of the mechanism are shared by most species studied: the mutation hot spot sequence AGY, and a preponderance of point mutations. These data suggest that some of the components of the machinery are shared between ectotherms and mammals. However, unique characters in particular species may have occurred by independent recruitment of novel factors onto the mechanism. A spotty phylogenetic distribution of gene conversion has also been revealed and can be explained if the two mechanisms share some characteristics. Both mutation and conversion require transcription-related sequences and/or factors. We theorized that targeting to V genes can be attained by a paused replication fork that has collided with a transcription complex stalled by a defective Ig transcription activator; the paused replication fork results in recruitment of an error-prone translesion synthesis DNA polymerase (somatic hypermutation) or of DNA repair mechanisms with homologous recombination (gene conversion). In addition, the pathway recruited in different species may be directed by the degree of homology among V genes.

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“…Th is idea is supported by the fi nding of equivalent cell clusters in the phylogeny. Th e presence of cell clusters of a 'similar composition' in the meningeal lymphohaematopoietic tissue of the sharks with extension to the ventricular lumen along the blood vessels might serve as an example [19] . It was suggested that these cell clusters develop aft er specifi c stimulation by harmful agents.…”

Section: Discussionmentioning

confidence: 99%

Evidence of Haematopoiesis within the Developing Human Diencephalon

Seitz

Hummel²,

Stein³

et al. 2006

Pathobiology

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Aim: The sites of haematopoiesis during human ontogeny can be correlated to the sites where haematopoiesis occurs in vertebrate phylogeny. As haematopoiesis has been described in the diencephalon and pituitary gland of water-inhabiting vertebrates we wanted to find out whether such a phenomenon also occurs in human embryos. Material and Methods: Paraffin-embedded specimens from the diencephalon and pituitary gland of human embryos at the 7th to 22nd gestational week and from adults were investigated by conventional histology and immunohistology for the presence of haematopoietic cells. Results: Cellular accumulations predominantly of erythroid and megakaryocytic lineage were identified in the floor of the developing diencephalon of the 7th/8th gestational week. At the older developmental stages of the 18th to 22nd gestational week loose aggregates of haematopoietic cells within the leptomeningeal spaces adjacent to the hypophyseal infundibulum were detected in 2 out of 7 cases analyzed. Conclusions: As it has been proposed that lymphohaematopoietic clusters occasionally occur within the brain in bone marrow-less vertebrates as a response to noxious agents, we speculate that this temporal appearance of haematopoietic cell clusters within the diencephalon floor in early human ontogeny could also be due to fetal immunomodulations.

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

Cited by 12 publications

References 27 publications

The cartilaginous skeleton of an elasmobranch fish does not heal

The cartilaginous skeleton of an elasmobranch fish does not heal

Evolution of somatic hypermutation and gene conversion in adaptive immunity

Evidence of Haematopoiesis within the Developing Human Diencephalon

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