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Ontogeny and peripheralization of thymic lymphocytes.
Science (New York, N.Y.)
|November 20, 1973
Summary
Thymic lymphocytes originate from the thymic primordium, not migrating stem cells. These thymic stem cells are the source for lymphocytes found in adult frog organs like the spleen and kidneys.
Area of Science:
- Developmental immunology
- Amphibian immunology
- Cellular origins of lymphocytes
Background:
- The origin of lymphocytes in lymphoid organs is a fundamental question in immunology.
- Previous hypotheses suggested lymphocytes could arise from intrinsic thymic elements or extrinsic blood-borne stem cells.
Purpose of the Study:
- To determine the ontogenic origin of thymic lymphocytes in frogs.
- To investigate whether lymphocytes develop from within the thymic primordium or migrate from elsewhere.
Main Methods:
- Reciprocal transplantation of undifferentiated thymic primordia between diploid and triploid chromosomally marked frog embryos.
- Analysis of lymphocyte origins in transplanted thymic tissues and other organs.
Main Results:
- Lymphocytes within the thymus were found to be derived from the thymic primordium itself.
- Chromosomal marking confirmed the thymic origin, excluding blood-borne stem cell contribution.
- Subsequent analysis showed that spleen, kidneys, and bone marrow lymphocytes in adults originated from these thymic stem cells.
Conclusions:
- Thymic lymphocytes are intrinsically derived from the thymic primordium.
- The thymus serves as the primary source of lymphocytes for multiple organs in adult frogs.
- This study clarifies the developmental pathway of lymphocyte generation in amphibians.