Ultrastructure and antigens in differentiation of thymus lymphocytes in human embryogenesis
Raĭtsina, S.S.; Kalinina, I.I.
Biulleten' Eksperimental'noi Biologii i Meditsiny 88(10): 470-473
1979
ISSN/ISBN: 0365-9615 PMID: 315244 Document Number: 142640
Thymus lymphocytes of 7-8 wk human embryos have nuclei of irregular form with 1-3 distinct nucleoli characterized by the absence of compact chromatin or heterochromatin. The electron-dense cytoplasm of these cells contains polysomes and an insignificant number of mitochondria. No receptors to sheep red blood cells and T-cell antigen are revealed on their surface. In 11-12 wk human embryos, a decrease in the size of thymus lymphocytes, appearance of heterochromatin in their nuclei and receptors to sheep red blood cells (79%) and T-cell antigen (60%) on the cell surface is observed. The quantity of compact chromatin in thymus lymphoid cells increases; the cells acquire definitive properties and structure.