IN BALB/c mice, surface immunoglobulin (Ig)-bearing B lymphocytes are first detectable by
immunofluorescence at 17 d gestation in the liver and spleen 1 . Explants of 14-d foetal liver …

THERE is good evidence that in birds a haemopoietic stem cells of yolk sac origin 1,2
differentiate into immunoglobulin-bearing lymphocytes in the bursa of Fabricius 3 . The …

We describe a novel cytoplasmic tyrosine kinase, termed BPK (B cell progenitor kinase), which
is expressed in all stages of the B lineage and in myeloid cells. BPK has classic SH1, SH2…

The bursa of Fabricius and the thymus are "central lymphoid organs" in the chicken, essential
to the ontogenetic development of adaptive immunity in that species. Surgical removal of …

A clonally diverse anticipatory repertoire in which each lymphocyte bears a unique antigen
receptor is the central feature of the adaptive immune system that evolved in our vertebrate …

The fine structure and micropinocytotic capabilities of epithelial cells closely associated with
lymphoid follicles in the chicken bursa of Fabricius, rabbit appendix, and mouse Peyer's …

Approximately 500 mya two types of recombinatorial adaptive immune systems appeared in
vertebrates. Jawed vertebrates generate a diverse repertoire of B and T cell antigen …

Although jawless vertebrates are apparently capable of adaptive immune responses, they
have not been found to possess the recombinatorial antigen receptors shared by all jawed …

Mice deficient in the cytokines tumor necrosis factor (TNF) or lymphotoxin (LT) α/β lack
polarized B cell follicles in the spleen. Deficiency in CXC chemokine receptor 5 (CXCR5), a …

The primary immunodeficiency disorders reflect abnormalities in the development and
maturation of cells of the immune system. These defects result in an increased susceptibility to …