« Lymphocytes Thymus-derived cells (T lymphocytes) mediate cellular immune responses; bone marrow-derived cells (B lymphocytes) are involved in humoral immunity. ...» Document abstract
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Language : english
medical studies
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date published
25/04/2008
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SummaryDevelopment of T & B Lymphocytes
Thymus-derived cells (T lymphocytes) mediate cellular immune responses; bone marrow-derived cells (B lymphocytes) are involved in humoral immunity. Both T and B lymphocytes are derived from precursor or stem cells in the marrow.
Precursors of T cells migrate to the thymus, where they develop some of the functional and cell surface characteristics of mature T cells. Through positive and negative selection, clones of autoreactive T cells are eliminated, and mature T cells migrate to the peripheral lymphoid tissues.
« Clearly, transplantation immunity can be evoked and expressed With blastocyst implantation, these cells persist in the speculated that LGLs are involved in the ...» Document abstract
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Language : english
medical studies
research papers
date published
26/11/2007
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SummaryOver the last half century, many attempts to explain the survival of the semiallogenic fetal graft have been proposed. One of the earliest explanations was based on the theory of antigenic immaturity of the embryo-fetus. This was disproved by Billingham (1964) who showed that transplantation (HLA) antigens are demonstrable very early in embryonic life. The trophoblasts are the only cells of the conceptus in direct contact with maternal tissues or blood and these tissues are genetically identical with fetal tissues. Another explanation was based on diminished immunological responsiveness of the pregnant woman. There is, however, no evidence for this to be other than an ancillary factor. In a third explanation, the uterus (decidua) is proposed as an immunologically privileged tissue site. Clearly, transplantation immunity can be evoked and expressed in the uterus as in other tissues. Therefore, the acceptance and the survival of the conceptus in the maternal uterus must be attributed to an immunological peculiarity of the trophoblasts, not the decidua.
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