title: B-cell precursors in early chicken embryos.
abstract: The ontogeny of B-cell precursors in chicken embryos from day 3 of incubation onwards has been studied. Purified antibodies to chicken Ig L, gamma, mu, alpha chains were used in a sensitive indirect immunofluorescence assayed on fixed cell smears and wax-embedded tissue sections; the location and morphology of immunoglobulin positive (Ig+) cells were determined either in phase contrast or after histological staining. Lymphoid cells containing small amounts of cytoplasmic immunoglobulin were found in 3 day and older embryonic yolk sac, 11 and 12 day blood, 11, 12 and 13 day bursal mesenchyme. cIg+ large basophilic cells were first seen in 14 day bursal follicles. It is concluded that cells enter the embryonic bursa at different developmental stages: some appear to be uncommitted stem cells, whilst others have already commenced B-cell maturation in an extra-bursal site.
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology; D002060:Bursa of Fabricius / Q000166:cytology / Q000276:immunology; D002642:Chick Embryo / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D007136:Immunoglobulins / Q000032:analysis; D013997:Time Factors; D015017:Yolk Sac / Q000166:cytology / Q000276:immunology
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins